Fast National ratings for Thursday, May 15, 2014.

"The Big Bang Theory" had its most-watched season finale to-date, far above last year's finale which went against an "American Idol" send-off, and led CBS to easy Thursday wins in all measures.

As usual, primetime results were mixed.

On the positive side, "American Idol" continued its pre-finale rise with big week-to-week gains, with "Hell's Kitchen" also getting a bump for FOX.

On the negative side, "Rosemary's Baby" continued to be a major disappointment for NBC, though the second part of the high-profile miniseries was steady from Sunday's dismal second hour.

Then there are the mixed results.

Some observers will rave that "Grey's Anatomy" got a big week-to-week bump for Cristina's departure. This is technically true, but "Grey's Anatomy" was down steeply last week, so this week's gains still put the finale below the numbers from two weeks ago, which isn't such an impressive bump at all.

Similarly, "The Vampire Diaries" finale was up a hair from last week in the key demo, but down significantly from last year's finale and, in fact, "TVD" was down from last week in total viewers.

On to the numbers...

Among adults 18-49, CBS averaged a 2.2 rating for Thursday night, beating out FOX's 1.9 rating in the key demographic. ABC was third with a 1.4 key demo rating, topping NBC's 1.0 key demo rating and the 0.6 key demo rating for The CW.

Overall, CBS averaged an estimated 8.99 million viewers and a  5.6 rating/10 share for Thursday primetime, comfortably ahead of the 6.66 million viewers and 4.1/7 for FOX. ABC was third with 5.47 million viewers and a 3.8/6, topping the 2.3/4 and 3.47 million viewers for NBC. The CW averaged 1.415 million viewers and a 1.0/2.

8 p.m. - CBS started primetime in first with finales for "The Big Bang Theory" (16.29 million viewers and a 4.8 key demo rating) and "The Millers" (9.88 million and a 2.4 key demo). FOX's "Hell's Kitchen" was second with 4.755 million viewers and a 1.7 rating among adults 18-49. NBC's "Hollywood Game Night" was third with 3.785 million viewers and a  1.1 key demo rating, topping the 3.575 million viewers and 0.6 key demo rating for ABC's "Grey's Anatomy" repeat. The CW's "The Vampire Diaries" finale averaged 1.57 million viewers and a 0.8 key demo rating.

9 p.m. - ABC won the 9 p.m. hour with 8.61 million viewers and a 2.5 rating among adults 18-49 for the "Grey's Anatomy" finale. FOX's "American Idol" was close behind with 8.56 million viewers and a 2.0 key demo rating. CBS' repeat of "Two and a Half Men" (7.58 million and a 1.8 key demo) and a new "Bad Teacher" (5.53 million and a 1.4 key demo) followed. NBC's "Rosemary's Baby" drew 2.912 million viewers and a 0.8 key demo rating for its first hour, still topping the 1.26 million viewers and 0.5 key demo rating for The CW's "Reign" finale.

10 p.m. - CBS won the 10 p.m. hour with 7.34 million viewers and a weak 1.4 key demo rating for the finale of "Elementary," which picked an odd time to hit a series low. ABC's "Black Box" was second with 4.23 million viewers and a 1.1 key demo rating. "Rosemary's Baby" got a bump for its last hour, rating to 3.71 million viewers and a 1.1 key demo rating.

All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.