NBC on Thursday attempted to put a positive face on the latest late-night results, which showed Conan O'Brien's Tonight show trailing David Letterman's Late Show in total audience despite the fact that CBS's Letterman was in reruns. Conan, it noted, continued to lead Letterman among the key 18-49 demographic. "The median age of Conan's audience last week was 47.1, more than 10 years younger than Letterman's 57.4 and 9 years younger than the 56.3 of ABC's Nightline ," the network added. In fact, however, ABC's Nightline beat both the NBC and CBS variety/talk shows with 3.36 million viewers to 3.27 for Letterman and 3 million for O'Brien.