Jay Leno's Tonight Show increased to a 1.1 adults 18-49 rating last week (April 26-30), a tenth of a point above of Conan O'Brien's Tonight Show in the ninth week of each show's run. However, there has been little difference between the two show's ratings trends since week 5 of their run's.
David Letterman's Late Show slipped back a tenth of a point in the adults 18-49 ratings vs. the previous week, and was again beaten by the Tonight Show as he has been each week since Jay returned.
Conan/Letterman (2009-10) week 1 ended 6/5/09. Leno/Letterman (2010-) week 1 ended 3/5/10.
The Conan/Letterman(2009-10) ratings do not include the final week the Tonight Show was in repeats prior to the Winter Olympics.
For historical reference, here are last season’s season-to-date averages through May 1, 2009:
11:35 p.m. ET
NBC “Tonight,” 1.4/6
CBS “Late Show,” 1.1/4
ABC “Nightline,” 1.1/4