Note: Both theand were in repeats in the latest week (May 31 - June 4). Unfortunately, I don't have easy access to information to compare the repeat status of the /Letterman weeks from 2009.
Jay Leno's1.0 adults 18-49 last week (May 31 -June 4) was even with the previous week, and one tenth of a ratings point below O'Brien's ratings trend, comparing the ratings for each show's fourteenth week. They've only been more than a tenth of a point apart once since the fifth week of each show's run.
Readers should note that 14 weeks into "(2009-10)" was the first week of September, 2009, as the broadcast TV year begins to show signs of life, but the 14th week of "Leno (2010-)" was the first full week of broadcast TV "summer" as things begin to slow down quickly.
/Letterman (2009-10) week 1 ended 6/5/09. Leno/Letterman (2010-) week 1 ended 3/5/10.
The/Letterman(2009-10) ratings do not include the final week the was in repeats prior to the Winter Olympics.
We have now passed Conan's 2009 start date (June 1). In another couple weeks, I will shift the start dates for the lines on the chart so that equivalent *calendar* dates line up, instead of the week sequence numbers. Or, I might just produce two charts each week, since it's little additional effort.