As they head into next week's upfront presentation of new shows to advertisers, broadcast network executives are struggling to lure back 18-49-year-old viewers who are increasingly deserting broadcast programming and switching to cable, the Internet, and video games instead. Today's (Friday) Los Angeles Times detailed the Exodus -- noting that this season Fox is down 9 percent in the demo, the CW 11 percent, and NBC is flat (without the Super Bowl skewing the numbers). Only CBS is up among younger viewers -- and only by about 3 percent at that. Some individual shows have taken big hits, with Fox's American Idol taking the hardest of them, losing 30 percent of its younger audience this season. Network programmers are hoping that they'll have better luck next season with shows aimed at younger viewers than they did last season, when not a single new show turned up on the list of top ten programs among total adults and only two did among the 18-49 demo, CBS's 2 Broke Girls and Fox's The X Factor -- at No. 9 and 10 respectively.