David Letterman’s ratings gains over Leno continue. First he tied Leno 3 weeks ago among adults 18-49 for the first time since Leno retook The Tonight Show in March. The two were tied for the past 3 weeks at a 0.9 rating and now, for the first time, Letterman came out on top last week for a clean sweep: victories in adults 18-49 (1.0/4 vs. 0.9/4 for Leno), adults  25-54 (1.3/5 vs. 1.2/5) and total viewers (3.8 million vs. 3.6 million). Compared to the same week last year, Letterman was up a tenth (11%) in 18-49 and down 4% in total viewers. Leno was down a tenth (10%) from what his temporary successor on The Tonight Show, Conan O’Brien delivered on the night last fall. In total viewers, Leno was up 50% as he has been bringing in older audiences. Overall, CBS’ Late Show and NBC’s The Tonight Show have been slow-moving ships stuck in the 0.9-1.0 demo range with only small upticks or slips week-to-week.