Thanks to Trekweb for the following info, which they got from futoncritic!:

Season Ratings Wrap-up! ENTERPRISE's Strong Start Secures 3rd Place Behind Alias and The X-Files; Viewers Lost at 58% After First Season

The 2001-2002 network television season is now behind us and it's time to judge how UPN's latest Star Trek offering performed. ENTERPRISE's strong start with 12.5 million viewers for the series pilot "Broken Bow" allowed it to secure 3rd place with a season average of 6.7 million viewers for first-run episodes, just ahead of CBS' limited 4-episode run of Wolf Lake (6.6 million) and The WB's late charging Smallville (6.5 million). ABC's new series Alias finish top dog, averaging over half a million more viewers (10.1 million) than FOX's The X-Files (9.3 million), which secured 2nd place in its 9th and final season. Both Alias and The X-Files were well ahead of the pack.

UPN's Roswell and Wolf Lake and The WB's Glory Days were clear losers of the season, well behind the pack.

Science Fiction/Fantasy Network Television Series
SEASON AVERAGE FOR FIRST-RUN EPISODES (based on number of viewers), 2001-2002

1) Alias (ABC) - 10.1 million (22 episodes)
2) The X-Files (FOX) - 9.3 million (20 episodes)*
3) Enterprise (UPN) - 6.7 million (26 episodes)*
4) Wolf Lake (CBS) - 6.6 million (4 episodes)
5) Smallville (WB) - 6.5 million (23 episodes)**
6) Dark Angel (FOX) - 6.0 million (21 episodes)***
7) Buffy the Vampire Slayer (UPN) - 5.3 million (22 episodes)*
8) Charmed (WB) - 4.7 million (22 episodes)*
9) Angel (WB) - 4.6 million (22 episodes)
10) Roswell (UPN) - 3.0 million (18 episodes)
12) Wolf Lake (UPN) - 2.6 million (4 episodes)****
12) Glory Days (WB) - 2.6 million (9 episodes)***

* including two-hour special presentation
** includes 2 two-hour special presentations
*** including a switch of time slots
**** does not include rebroadcast of pilot on 4/3/02, originally shown on CBS, 9/26/01

Science Fiction/Fantasy Network Television Series
TOP-RANKED SEASON PREMIERES (based on number of viewers), 2001-2002

1) Alias, 9/30/01 (ABC) - 9.5/14 (15.0 million)
2) Enterprise, 9/26/01 (UPN) - 7.0/11 (12.5 million)
3) The X-Files, 11/11/01 (FOX) - 6.5/10 (10.6 million)
4) Smallville, 10/9/01 (WB) - 5.4/8 (8.4 million)
5) Buffy the Vampire Slayer, 10/2/01 (UPN) - 4.3/7 (7.7 million)
6) Wolf Lake, 10/10/01 (CBS) - 5.1/8 (7.5 million)
7) Dark Angel, 9/28/01 (FOX) - 4.7/9 (7.4 million)
8) Charmed, 10/4/01 (WB) - 3.9/6 (6.0 million)
9) Angel, 9/24/01 (WB) - 3.2/5 (5.0 million)
10) Roswell, 10/9/01 (UPN) - 2.4/4 (3.9 million)
11) Glory Days, 1/16/02 (WB) - 2.3/3 (3.5 million)
12) Wolf Lake, 4/3/02 (UPN) - 1.9/3 (3.0 million)*

* UPN repeat broadcast of Wolf Lake pilot originally showed on CBS, 9/26/01

Science Fiction/Fantasy Network Television Series
TOP-RANKED SEASON FINALES (based on number of viewers), 2001-2002

1) The X-Files, 5/19/02 (FOX) - 7.5/12 (13.2 million)
2) Alias, 5/12/02 (ABC) - 6.5/10 (11.3 million)
3) Smallville, 5/21/02 (WB) - 3.8/6 (6.0 million)
4) Dark Angel, 5/23/02 (FOX) - 3.7/7 (5.7 million)
5) Enterprise, 5/22/02 (UPN) - 3.3/6 (5.3 million)
5) Buffy the Vampire Slayer, 5/21/02 (UPN) - 3.3/5 (5.3 million)
7) Charmed, 5/16/02 (WB) - 3.4/5 (5.2 million)
8) Angel, 5/20/02 (WB) - 2.7/4 (4.6 million)
9) Roswell, 5/14/02 (UPN) - 2.0/3 (2.8 million)

NOTE: The WB's Glory Days and CBS/UPN's Wolf Lake are not included in these rankings since they did not have formal season finales as such.

The Alias series pilot secured the top spot as the most watched first-run episode of the 2001-2002 season with 15.0 million viewers, easily outdistancing the series finale of The X-Files (13.2 million) and the series pilot of Enterprise (12.5 million). Because of The X-Files' strong finish, it was the only network series which was able to secure a higher number of viewers at the end of the 2001-2002 season than it began with (see below). The WB's Angel and Charmed, though well back in the pack in terms of average number of viewers, both exhibited a good degree of consistency during the season. Both performed well in terms of the difference between where they started the season and where they ended up, with the smallest drops in audience numbers for any series with a full season run of episodes; Angel only losing 8.0 % of its season premiere and Charmed only 13.3 % of its season premiere. The WB/UPN heavyweights possessed the greatest loss of viewers from their season premieres to their season finales with Smallville losing 28.6 %, Buffy the Vampire Slayer losing 31.4 % and Enterprise losing an astounding 57.6 %; a loss of viewers more than 50% greater of that of its nearest competitor, The WB's dismal performing Glory Days - now mercifully put out of its misery.

Science Fiction/Fantasy Network Television Series
PERCENTAGE GAIN/LOSS BETWEEN SEASON PREMIERE AND FINALE, 2001-2002

1) The X-Files (FOX), + 24.5 %
2) Angel (WB), - 8.0%
3) Charmed (WB), - 13.3 %
3) Wolf Lake (UPN), - 13.3 %***
5) Wolf Lake (CBS), - 18.7 %**
6) Dark Angel (FOX), - 23.0 %*
7) Alias (ABC), - 26.6 %
8) Roswell (UPN), - 28.2 %
9) Smallville (WB), - 28.6 %
10) Buffy the Vampire Slayer (UPN), - 31.2 %
11) Glory Days (WB), - 31.4 %*
12) Enterprise (UPN), - 57.6 %

* including a switch of time slots
** based on four episode run
*** based on UPN repeat of pilot shown on CBS, 9/26/01

Science Fiction/Fantasy Network Television Series
MOST WATCHED FIRST-RUN EPISODES (based on number of viewers), 2001-2002

1) Alias, 9/30/01 (ABC) - 9.5/14 (15.0 million)*
2) The X-Files, 5/19/02 (FOX) - 7.5/12 (13.2 million)**
3) Enterprise, 9/26/01 (UPN) - 7.0/11 (12.5 million)*
4) Smallville, 10/9/01 (WB) - 5.4/8 (8.4 million)*
5) Buffy the Vampire Slayer, 10/2/01 (UPN) - 4.3/7 (7.7 million)*
6) Dark Angel, 10/12/01 (FOX) - 4.4/8 (7.6 million)
7) Charmed, 10/4/01 (WB) - 3.9/6 (6.0 million)*
8) Angel, 5/6/02 (WB) - 3.1/5 (5.2 million)
9) Roswell, 10/9/01 (UPN) - 2.4/4 (3.9 million)*

*denotes season premiere
**denotes season finales

NOTE: The WB's Glory Days and CBS/UPN's Wolf Lake are not included.

The WB's Angel and FOX's Dark Angel were the only network television series which secured their largest audience for a first-run episode which was not a season premiere or finale.

Science Fiction/Fantasy Network Television Series
LEAST WATCHED FIRST-RUN EPISODES (based on number of viewers), 2001-2002

1) Alias, 4/14/02 (ABC) - 4.9/8 (7.8 million)
2) The X-Files, 3/31/02 (FOX) - 4.4/7 (7.7 million)
3) Smallville, 4/23/02 (WB) - 3.4/5 (5.5 million)
4) Dark Angel, 12/14/01 (FOX) - 3.3/6 (5 million)
5) Enterprise, 2/27/02 (UPN) - 3.0/5 (4.5 million)
6) Buffy the Vampire Slayer, 5/7/02 (UPN) - 2.7/4 (4.1 million)
7) Angel, 12/10/01 (WB) - 2.5/4 (3.8 million)
8) Charmed, 1/17/02 (WB) - 2.4/4 (3.4 million)
9) Roswell, 1/1/02 (UPN) - 2.0/3 (2.9 million)

NOTE: The WB's Glory Days and CBS/UPN's Wolf Lake are not included. It is interesting to note that the least-watched first run episodes for network series do not appear to be not strongly linked to any specific time of the season, with least watched episodes occurring throughout the calender in December (Dark Angel, Angel), January (Roswell, Charmed), February (ENT) March (The X-Files), April (Alias, Smallville) and May (BVS).

Science Fiction/Fantasy Network Television Series
PERCENTAGE DIFFERENCE BETWEEN MOST AND LEAST WATCHED FIRST-RUN EPISODES, 2001-2002

1) Roswell (UPN), - 25.6 %
2) Angel (WB), -26.9 %
3) Dark Angel (FOX), -34.2 %
4) Smallville (WB), - 34.5 %
5) The X-Files (FOX), -41.6 %
6) Charmed (WB), -43.3 %
7) Buffy the Vampire Slayer, - 46.8 %
8) Alias (ABC), - 48.0 %
9) Enterprise (UPN), -64.0 %

UPN's Roswell showed the least amount of difference between its most and least watched first-run episodes. However, this is deceptive due to its low season average in terms of viewers and is more of an indication that very few people were watching Roswell (small but loyal). When indexed to its averaged audience size (see below), we can see that it falls down the chart in terms of relating consistency and audience size. Contrast this to The WB's Angel, which scored the second least amount of change between its most and least watched episodes. When indexed to its average audience size, its performance remained strong (percentage difference/season average = 5.8 for Angel whereas Roswell scored an 8.5 for the same measurement, the lower the number the better the performance). In this way, we can measure performance in terms of consistency related to typical audience size. When we do this, we can see that The X-Files, Alias and Smallville all performed well and that Buffy the Vampire Slayer, Charmed and Enterprise didn't perform nearly as well with Enterprise bringing up the rear (Charmed's low score, like Roswell, is an indication of a small but reasonable loyal audience). Basically, what differentiates Angel's small audience from Charmed's and Roswell's is Angel's viewers are more loyal - and hence more likely to be watching week to week, resulting in fewer fluctuations in viewer numbers. This no doubt contributed to Angel's renewal by The WB rather than its rumored drop and move to its sister series' UPN network. There is a very clear separating out of the network series, with The X-Files, Alias, Smallville, Dark Angel and Angel forming a top tier and Roswell, Buffy the Vampire Slayer, Charmed and Enterprise forming a lower tier.

Science Fiction/Fantasy Network Television Series
"PERFORMANCE" - RELATIVIZED DIFFERENCE BETWEEN MOST AND LEAST WATCHED FIRST-RUN EPISODES*, 2001-2002

1) The X-Files (FOX) - 4.5
2) Alias (ABC) - 4.8
3) Smallville (WB) - 5.3
5) Dark Angel (FOX) - 5.7
5) Angel (WB) - 5.8
6) Roswell (UPN) - 8.5
7) Buffy the Vampire Slayer - 8.8
8) Charmed (WB) - 9.2
9) Enterprise - 9.5

* Indexed to seasonal average for number of viewers; Percentage difference divided by the seasonal average. The smaller the number, the better a show performed in relation to its mean audience size. This relativizes the comparison to take into account that more watched series can lose more viewers and still perform well in comparison to less watched shows which can not afford to lose equivalent numbers of viewers.

Science Fiction/Fantasy Genre Network Television Series
NOVEMBER SWEEPS AVERAGE FOR FIRST-RUN EPISODES (based on number of viewers), 2001-2002

1) The X-Files (FOX) - 9.6 million (3 episodes)
2) Alias (ABC) - 9.4 million (2 episodes)
3) Enterprise (UPN) - 7.0 million (5 episodes)
4) Dark Angel (FOX) - 6.7 million (3 episodes)
5) Smallville (WB) - 6.5 million (5 episodes)
6) Buffy the Vampire Slayer (UPN) - 5.4 million (5 episodes)
7) Charmed (WB) - 4.8 million (3 episodes)
8) Angel (WB) - 4.7 million (4 episodes)
9) Roswell (UPN) - 2.9 million (5 episodes)

Science Fiction/Fantasy Genre Network Television Series
FEBRUARY/MARCH SWEEPS AVERAGE FOR FIRST-RUN EPISODES (based on number of viewers)*, 2001-2002

1) Alias (ABC) - 9.6 million (5 episodes)
2) The X-Files (FOX) - 9.1 million (2 episodes)
3) Smallville (WB) - 6.5 million (5 episodes)
4) Enterprise (UPN) - 5.6 million (4 episodes)
5) Dark Angel (FOX) - 5.5 million (3 episodes)**
6) Buffy the Vampire Slayer (UPN) - 5.2 million (5 episodes)
7) Charmed (WB) - 4.5 million (4 episodes)
8) Angel (WB) - 4.4 million (4 episodes)
9) Roswell (UPN) - 3.0 million (4 episodes)
10) Glory Days (WB) - 2.5 million (4 episodes)

* adjusted for NBC 2-week coverage of the Salt Lake City Winter Olympics
** change of time slot since November sweeps

Science Fiction/Fantasy Network Television Series
MAY SWEEPS AVERAGE FOR FIRST-RUN EPISODES (based on number of viewers for series with more than one episode airing during the period), 2001-2002

1) The X-Files (FOX) - 10.8 million (5 episodes)*
2) Alias (ABC) - 9.7 million (2 episodes)
3) Smallville (WB) - 6.0 million (5 episodes)*
4) Enterprise (UPN) - 5.2 million (5 episodes)
5) Charmed (WB) - 5.0 million (3 episodes)
7) Angel (WB) - 4.7 million (4 episodes)
7) Buffy the Vampire Slayer (UPN) - 4.7 million (4 episodes)
8) Roswell (UPN) - 2.9 million (3 episodes)

* includes a 2-hour special presentation