Ratings Chart Attack!

Fox’s “American Idol” welcomed its 13 finalists for the season on Thursday night, and won the distinction of being the No. 1 show Thursday night.

During the 8 p.m. hour, “Idol’s” wild card round scored a 7.5 rating/20 share among adults 18-49 and 21.2 million viewers, according to preliminary Nielsen Media Research figures.

The show’s overall performance is estimated to increase once the five-minute overrun into the 9 p.m. hour is factored in later today. Last night’s episode was up 6% from last week’s episode, but down 20% from its comparable night last year, making It“s the second lowest-rated episode of the season. A new “Hell’s Kitchen” (4.6/12, 10.6 million) posted a 6% improvement over last week. Overall, Fox finished on top of the ratings with a 6.1/16 (15.9 million).

New episodes on CBS gave the network second place for the night with an average 4.0/11 (15 million). At 8 p.m. a new episode of “Survivor: Tocantins” scored a 3.8/10 (12 million), matching its previous series low (excluding a Thanksgiving episode). New episodes of “CSI” (5.3/13, 20.8 million) and “Eleventh Hour” (3.0/8, 12.2 million) matched their previous season-to-date averages.

NBC finished third (3.2/9, 7.2 million) with solid performances by “The Office” (4.5/11, 8.6 million) and “ER” (3.5/10, 8.8 million), which won the 10 p.m. hour and scored its best delivery in two months. In the 8 p.m. hour, “My Name Is Earl” pulled a 2.2/6 (5.6 million) and “Kath & Kim” earned a 1.8/5 (4.2 million). A new episode of “30 Rock” (3.8/9, 7.4 million) was also on the high side.

A new series low for “Ugly Betty”(1.7/5, 6.4 million) and repeats of “Grey’s Anatomy” and “Private Practice” gave ABC fourth for the night (1.6/4, 5.5 million).

The CW averaged a 0.8/2 (2.1 million) with repeats of “Smallville” and “Supernatural.”