"American Idol" triumph drew nearly 6 million fewer viewers than last year's finale.

LOS ANGELES (Reuters) - The "American Idol" triumph of 17-year-old Jordin Sparks drew nearly 6 million fewer viewers than last year's finale, in the latest sign that U.S. television's highest-rated show may have finally hit its peak.

According to a final tally from Nielsen Media Research on Thursday, 30.7 million fans watched as the Arizona teenager was crowned the youngest champion at the end of the sixth installment of Fox network's amateur singing contest.

The Wednesday night total is down 16 percent from the 36.4 million who tuned in to see gray-haired soul crooner Taylor Hicks claim victory at the conclusion of last year's competition.

For the season as a whole, "American Idol" was down slightly in average overall audience compared with 2006, and off a bit more in ratings for viewers aged 18 to 49, the key young-adult crowd most prized by advertisers.

That marks the first year-to-year decline in the show's Nielsen numbers since its 2002 inception, despite media hype and Internet buzz this year surrounding two contestants -- the racy photos of Antonella Barba and the wacky-haired sensation stirred by Sanjaya Malakar.

Moreover, the show that has built Fox into a prime-time powerhouse for young viewership has continued to grow steadily older.

Nielsen figures show the median age of "Idol" viewers has risen from 34 to 41 during the past five years, and that viewers over 50 now account for about a third of the show's audience, compared to less than 20 percent in 2003.

MOST WATCHED SERIES

Still, "American Idol" remains the most watched U.S. TV series overall, and the most highly rated in the 18-49 category for a fourth straight year, Fox said.

"This is far and away the biggest show on television and will continue to be the biggest show on television," Fox network spokesman Scott Grogin said. "We're looking forward to next season."

Industry experts say "American Idol" has suffered, in part, from a general decline in broadcast TV audiences that has taken its toll on many of prime time's biggest hits this past season. Some of those losses are attributed to the growing popularity of digital video recorders (DVRs).

Year-to-year declines for "Idol" were most pronounced for the Tuesday performance telecasts as the field of contestants narrowed, suggesting this season's talent pool generated less enthusiasm from fans than last year.

But Sparks was chosen as winner over 25-year-old Blake Lewis via a telephone vote in which a record 74 million votes were cast.

The live, two-hour finale, featuring appearances by such recording stars as
Gwen Stefani,
Bette Midler,
Tony Bennett and Green Day, as well as four of the five past "Idol" winners, brought a dramatic close to the 2006-07 U.S. broadcast season.

Fox, a unit of News Corp., finished the season as the leading network in 18-49 ratings for a third straight year and was the only one to increase its overall average audience year to year, up 3 percent from last season.

The second-season "Idol" finale in May 2003, when
Ruben Studdard was crowned the winner, stands as the most watched of any episode of the series, averaging 38.1 million viewers.