In the four weeks that Jay Leno's Tonight Show overlapped with Conan's on a calendar week basis (2010 vs. 2009) he's finished behind Conan. However, that was during the "premiere" phase for Conan. It was the fifth week of Conan's run in the summer of 2009 when he settled near his "hubbub free" ratings level of between a 1.0 and 1.1 adults 18-49 rating.
If Jay can hold at the 1.0 adults 18-49 rating he scored last week (June 21-25), he'd tie Conan's ratings for much of the summer. Stay tuned.
The folks dwelling on Leno beating Letterman (which he did again last week) miss the point that beating the competition is important only in press releases (and to sites like ours that focus on the horserace) not to the network's business. What matters to NBC are a show's absolute ratings (and their trend) which correlate to its advertising potential. NBC's ad revenue is based on the Tonight Show's ratings, not whether it beat the Late Show or not.
CBS, of course, cares about Letterman's Late Show ratings and their trend. On that basis, the fact that Dave had identical ratings to last summer for the last three weeks is pretty good in the broadcast television world where "flat is the new up".
The first chart aligns the ratings weeks for the shows to their calendar weeks.
The second chart shows the Leno/Conan ratings in the same sequential week of their run. Since, the first chart now has 4 weeks of calendar week overlap, this is likely the last week I will create the sequential week chart which was only interesting to me prior to the calendar overlap.
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.