After two weeks of Jay Leno's Tonight Show tying Conan's on a calendar week basis (2010 vs. 2009) Leno's Tonight Show ratings dropped back behind Conan's Tonight Show ratings for the comparable calendar week (July 19-23, 2010 vs. July 20-24, 2009).
Leno trailed Conan's 2009 week performance by one tenth of an 18-49 ratings point. Leno still came out ahead of Letterman, but Letterman was flat year over year with a 0.8 adults 18-49 rating in both years.
The chart shows the late night adults 18-49 weekly average ratings for 2009 and 2010.
Note: The week ending 7/2/2010, the Tonight Show was in repeats, and was delayed by Wimbledon coverage. The week of 7/9/2010 the Late Show was in repeats, and both shows Monday airings were excluded because of the holiday. Fo the weeks ending 7/16 and 7/23, Late Show was a repeat only on Friday.
No more chart of the sequential weeks comparison between Conan and Leno. That chart was always a bit apples/oranges because of the different seasons. While before the calendar runs of the shows overlapped we had to make do, now that we have some of the same time period to compare, the sequential chart has been retired.