Fast National ratings for Thursday, April 15, 2010.
 
"CSI" was Thursday's most watched show, while "Survivor: Heroes vs. Villains" was the night's best in the key demo, so it's no wonder that CBS claimed the evening's key ratings races.
 
Meanwhile, NBC got solid demo numbers from a "Saturday Night Live" documentary special and "FlashForward" went back to losing viewers.
 
Among adults 18-49, CBS averaged a 3.1 rating for the night, topping the 2.6 rating for FOX and ABC's 2.4 rating in the all-important age range. ABC and The CW tied for fourth with a 1.3 rating.
 
Overall, CBS averaged an estimated 12.23 million viewers to go with a 7.5 rating/13 share. FOX's 5.1/9 was second, topping the 3.7/7 for NBC. ABC's 3.1/5 was fourth, comfortably holding off the 1.6/3 for The CW in fifth.
 
"Survivor: Heroes vs. Villains" kicked Thursday off in first for CBS with a 7.1/12, also delivering a 3.7 demo rating. FOX's "Bones" was a strong second with a 6.2/11, also improving slightly from last week in the demo. ABC's "FlashForward," inexplicably up last week, fell to a 3.4/6 dropping under 5 million viewers and a to a 1.4 demo rating. NBC's two episodes of "The Office" were fourth. The CW's "The Vampire Diaries" had a 1.8/3 and although it last half-a-million viewers from last week, "VD" did a 1.5 demo rating to beat "FlashForward."
 
In the 9 p.m. hour, "CSI: Crime Scene Investigation" had an 8.1/14 for CBS, drawing 13.05 million viewers and winning the hour with a 3.0 rating in the demo. NBC's tribute to last decade on "Saturday Night Live" was second with a 4.2/7 and in the demo. FOX's "Fringe" had a 4.1/7 and actually beat NBC in total viewers, showing a little improvement from last week. ABC's "Grey's Anatomy" repeat was fourth. The CW's "Supernatural" had a 1.5/2 for the hour.
 
A repeat of "The Mentalist" had a 7.5/13 to win the 10 p.m. hour for CBS. NBC's "SNL" special was second overall with a 4.2/8 and won the hour in the demo with a 3.0 rating. ABC's repeat of "Private Practice" was 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.
Dan-feinberg-med
A long-time member of the TCA Board and a longer-time blogger of "American Idol," Dan Fienberg writes about TV, except for when he writes about movies or sometimes writes about the Red Sox. But never music. He would sound stupid talking about music.