Fast National ratings for Thursday, May 19, 2011.
 
NBC got big demo numbers for its "Office" season finale, while the two-hour finale of "The Mentalist" brought viewers to CBS, but there was no stopping "American Idol," which carried FOX to yet another Thursday ratings win.
 
Among adults 18-49, FOX averaged a 4.7 rating for the night, far ahead of CBS' 2.8 rating in the key demographic. ABC's 2.5 rating and the 2.4 rating for NBC followed. The CW, airing a repeat of last week's "Smallville" finale, averaged a 0.5 rating.
 
Overall, FOX averaged an estimated 15.62 million viewers and a 9.1 rating/15 share for the night. CBS was a solid second with a 7.7/12 and 12.49 million viewers. There was another big drop to ABC's 5.0/8 and 7.54 million viewers and then to NBC's 2.9/5 and 4.66 million viewers. The CW's 0.8/1 and 1.32 million viewers lagged.
 
8 p.m. - "American Idol" led the 8 p.m. hour for FOX with 21.19 million viewers and a  6.2 rating among adults 18-49 for the season's final Thursday episode. CBS was second with "The Big Bang Theory" (11.12 million and a 3.5 demo) and "Rules of Engagement" (8.795 million and a 2.5 demo rating). ABC's "Wipeout" averaged 5.59 million viewers and a 1.7 demo rating, easily beating the 2.92 million viewers for a pair of "Office" repeats on NBC. The CW's "Smallville" trailed with 1.29 million viewers.

9 p.m. - Things got competitive in the 9 p.m. hour, with CBS' "The Mentalist" winning overall with 12.67 million viewers, but finishing a distant fourth with a 2.4 demo rating. "Bones" was second overall for FOX with 10.045 million viewers, but third in the key demo with a 3.2 rating. ABC's "Grey's Anatomy" finale was third in viewers with 9.58 million, but second with a 3.4 key demo rating. That meant that even though "The Office" was a distant fourth with 7.07 million viewers, it actually won the hour among adults 18-49 with a 3.8 demo rating. The CW was fifth with 1.35 million viewers for the end of the "Smallville" finale.
 
10 p.m. - "The Mentalist" improved to 14.84 million viewers and a  3.0 demo rating to rule the 10 p.m. hour for CBS. ABC's "Private Practice" averaged 7.47 million viewers and a 2.5 demo rating for second. NBC's two-episode "Parks and Recreation" season-ender averaged 3.98 million viewers and a 2.2 demo rating for third.
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.