Are you surprised at how old late-night TV viewers are? "While Mr. Leno now has a median age of 56, with Mr. Letterman at 54, 'Nightline' at 55, Mr. Ferguson and Mr. Kimmel both at 52, and even NBC’s younger act, Jimmy Fallon, at 50." Cable audiences are younger but really not by much.
Of course, Conan O'Brien was supposed to bring younger viewers to The Tonight Show but that never happened. The surprise: "Mr. Leno has drawn the biggest audiences in most age groups almost every night since returning March 1." If I were a Fox affiliate, I'd stick to re-runs too.