Maybe it doesn’t matter who sits in the Tonight Show chair after all. NBC’s The Tonight Show with Jay Leno posted a 1.0 rating among adults 18-49 during premiere week, matching the performance of The Tonight Show with Conan O’Brien the same week last year. (In total viewers, the older-skewing Leno was up 58%). It was a close race among Leno, CBS’ Late Show with David Letterman and Nightline last week. Leno won in both total viewers (3.79 million vs. 3.78 million for Letterman) and adults 18-49, where he was tied with Nightline at a 1.0 rating, followed by Letterman with a 0.9. In actual 18-49 viewers, Letterman was virtually tied with Nightline (1.24 million vs. 1.25 million), while Leno drew 1.33 million. Letterman was down year-to-year in both total viewers (24%) and 18-49 (25%). Last year, Letterman’s average was boosted by an appearance by President Barack Obama, while this year his premiere week guest lineup featured former president Bill Clinton and actor Joaquin Phoenix.