Fox's American Idol drew 18.19 million viewers Wednesday night. That was more than all of the other broadcast networks drew combined , but it was still way off previous seasons' numbers. Among adults 18-49 ratings were down 9 percent from last Wednesday and down a whopping 34 percent from the comparable week a year ago, according to TVbytheNumbers.com. For its third installment on Wednesday night a year ago, the talent contest drew 25.16 million total viewers, but a good number of those may have been tuning in out of curiosity to see how new judges Steven Tyler and Jennifer Lopez were adapting to their roles as judges. Nevertheless, the decline in ratings may be worrisome for Fox, which No Doubt guaranteed advertisers ratings similar to last year's and may be forced to give them free "make goods" if ratings don't substantially improve.