Ratings: American Idol Debut Suffers Biggest Decline in Its History

The two-hour Season 11 premiere ofAmerican Idol— the nation's most-watched prime-time program for the past eight seasons — attracted 21.6 million people and posted a 7.2 rating among 18-to-49-year-olds, down roughly 17 percent and 26 percent, respectively, compared with last year's premiere.

A year ago, Idol debuted to 26.1 million people, down 13 percent from 2010's 29.9 million, according to preliminary Nielsen figures at the time — which also showed a more precipitous drop in the industry-prized demographic, 18 percent. The Fox show scored a 9.7 rating in the demo, compared to 11.8 in 2010. The numbers have declined some 10 to 15 percent per season for five years.

Check out our first American Idol recap of the season

Still, the show far outpaces every other show — well, except NCIS — and certainly runs way ahead of the knockoff shows it's spawned, The X Factor and The Voice. On Wednesday night, it had a bigger audience than all of its competition combined.

The show took a bite out of every competing show's viewership, particularly the four ABC sitcoms — three of which hit season lows — and the two on NBC, where Chelsea Handler's comedy plummeted by more than 30 percent in Week 2.

On basic cable, Monday night's episode of Bravo's The Real Housewives of Beverly Hills set a series record, attracting 2.8 million.

Check out the rest of the day's news on TVGuide.com

8 p.m.
CBS: NCIS[rerun]9.07 million viewers (1.5 demo rating)
ABC: The Middle 8.15 million (2.6); Suburgatory  7.02 million (2.5)
Fox: American Idol 21.6 million (7.2) {8-10 p.m.}
NBC: Whitney 4.30 million (1.6); Are You There, Chelsea? 4.27 million (2.3)
CW: One Tree Hill1.52 million(0.9)