And the Oscar for lowest-rated Oscar ceremony goes to: The 2008 Oscars!

As spectacles go, ratings for the 80th Annual Academy Awards were less than spectacular. The ceremony averaged 29.16 million viewers Sunday evening, down distressingly from the 40.17 million who watched last year. And the show lost nearly 7 million viewers over the course of the 2.5 hours it was on the air in prime time on the East Coast.

By contrast, “American Idol” averaged 28.84 million viewers last Tuesday, and without having the likes of George Clooney, Jack Nicholson, Cate Blanchett and Nicole Kidman on hand.

The prior low: 2003’s 33 million viewers.

What accounted for the severe dropoff? Let’s take a look:

5:30 p.m.: Show begins with Jon Stewart’s opening monologue: 32.27 million viewers.

6 p.m.: Sigh … another montage, of past Best Supporting Actor winners. Down to 30.7 million.

6:30 p.m.: They’re handing out the Oscars for Live-Action and Animated Short Films. 630,000 more viewers bail out, leaving ABC with 30.07 million.

7 p.m.: Kristin Chenoweth’s overstuffed production number, “That’s How You Know,” sends nearly 3 million more audience members fleeing. Also, everyone on the East Coast switches over to CBS to watch the diluted version of an 18-month-old episode of “Dexter.” Down to 27.34 million.

7:30 p.m.: Some old guy gets an honorary Oscar, causing more viewers to wander off: 25.42 million are still hanging in there.

Numbers for the rest of the evening weren’t available, but it seems likely that the only people watching by the time “No Country For Old Men” won Best Picture were those live-blogging the show.