Fast National ratings for Thursday, May 20, 2010.
 
On a night of big finales on NBC, CBS, ABC and FOX, it was the two-hour "Grey's Anatomy" season-ender that ruled. But once again, ABC's already cancelled "FlashForward" delivered low enough ratings to help CBS split the night.
 
Among adults 18-49, ABC was in control with a 4.1 rating. CBS' 2.6 rating and the 2.4 ratings for both NBC and FOX followed in the key demographic. The CW's 0.5 rating was fifth.
 
Overall, though, CBS averaged an estimated 12.45 million viewers to go with a 7.7/13, nipping the 7.6/13 and 11.77 million viewers for ABC. FOX was a distant third with a 4.6/8, beating the 3.2/5 for NBC. The CW trailed again with a 0.9/2.
 
FOX's season finale of "Bones" ruled the "Survivor"-free 8 p.m. hour, winning with a 5.7/10 overall and a 2.8 demo rating. CBS finished second with overall with a repeat of "The Mentalist." ABC's "FlashForward" was well back in third with a 3.5/6. NBC's "Community" and "Parks & Regreation"  finales averaged a 2.9/5 between them and finished second in the hour with a 2.1 demo rating. The CW's repeat of "Smallville" had a 1.0/2 for fifth.
 
Things were close in the 9 p.m. hour. ABC's "Grey's Anatomy" had the ratings advantage with a 9.0/15 and easily won the key demo with a 4.8 rating. CBS' "CSI: Crime Scene Investigation" had an 8.6/14, but averaged more viewers than ABC for the hour. NBC's "The Office" and "30 Rock" had a 3.7/6 and a 3.1 demo rating, both third. FOX's "Fringe" finale was one of the few Thursday programs to drop from last week, doing a 3.6/6 and a 2.0 demo rating. The CW was fifth with another repeat.
 
ABC's second "Grey's Anatomy" hour was fully in control at 10 p.m. with a 10.2/17 and a 5.9 demo rating. CBS' "The Mentalist" was a close second with a 9.3/16 and a 3.2 rating in the demo. That left NBC's "The Marriage Ref" in a distant 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.