_VB11116American Idol’s ninth season bowed out last night with the franchise’s lowest-rated finale. 24.2 million viewers (8.2 rating in adults 18-49) tuned in to see a parade of (mostly former) music stars, including Alice Cooper, Janet Jackson, the Bee Gees, Michael McDonald, Chicago, Alanis Morissette and Christina Aguilera, as they performed alongside Idol finalists leading to the crowning of Lee DeWyze as the new American Idol. That was down from the previous low Idol finale benchmark in adults 18-49, last year’s closer, which averaged a 10.0 rating in 18-49. In total viewers, this year’s finale was slightly higher that the first Idol finale in the summer of 2002, which drew the smallest audience to date, 23 million viewers. (The performance Idol finale on Tuesday also hit all-time lows.) With the voting results leaked earlier in the day, the main intrigue of the night was how uncomfortable the music veterans would look sharing the stage with the Idol contestants (very), how much of the finale would be devoted to the send-off of judge Simon Cowell (a lot), and how off-the-charts Paula Abdul would be in her Idol return (she wore a pink tutu!). The other networks stayed largely out of the fray with repeats except for CBS. It aired the season finales of Criminal Minds (3.1/8 in 18-49) at 9 PM, which hit a season low, down 11% from last season’s ender, and CSI:NY (2.7/8) at 10 PM, which was up 8% from last week but down 16% from last year’s finale. (Only the fast nationals for American Idol have been time-zone adjusted. Final ratings will be available later today.)