Nielsen's numbers for the first four weeks of the fall television season are in, and the figures don't look great for the three traditional major TV networks, The Wall Street Journal reports. NBC's 18- to 49-year-old audience--those viewers most valuable to advertisers--is down the most at 9.3 percent from the same period last year, a decrease less dramatic than those at its rivals, ABC and CBS, which saw their under-50 audiences decrease 5.8 percent and 2.3 percent, respectively. Among the four major network only Fox saw a viewership boost this year with an 11 percent increase in the demographic. The Journal assesses the damage at NBC, whose prime-time lineup has been stuck in fourth place since 2004:

Part of NBC's problem: Its biggest hits, such as "The Office," are aging. There are some signs of life this fall with a pair of new comedies, "Whitney" and "Up All Night," but those shows are pulling in few viewers compared to new comedies like Fox sitcom "New Girl" and "Two Broke Girls" on CBS, and rank at Nos. 42 and 44, respectively, this season among viewers between 18 and 49 years old.

Comedies, as The New York Times notes, seem to be where audience growth is at this year: "comedy has surged back this fall, elbowing past those other genres to reclaim supremacy among viewers. So far this season, sitcoms occupy seven of the top 10 spots among entertainment programs (not counting football) in the category of most financial importance to network executives — viewers ages 18 to 49." Why is that? New comedic talent, sure, but also the economy. "Comedy thrives during economic downturns. You know, if you’ve had a bad day, laughter is a better remedy than watching a coroner pick shrapnel out of some poor guy’s private parts," Chuck Lorre, creator of Two and a Half Men and The Big Bang Theory, tells The Times.