FX’s original comedy series combination of It’s Always Sunny in Philadelphia and The League posted stellar ratings Thursday night, with both shows delivering all-time series highs in Adults 18-49 and Adults 18-34, as well as other key demos.

The season six premiere of It’s Always Sunny in Philadelphia ranked as the #1 program on cable Thursday night in delivery of Men 18-49 and Men 18-34 (topping MTV’s Jersey Shore), and beat every broadcast network at 10 PM in both demos.

Sunny (10PM, 9/16) delivered 1.83 million Adults 18-49 and 1.46 million Adults 18-34, besting previous series highs in those demos by +3% (season five premiere, 9/17/09), an amazing accomplishment for a show in its sixth season. Sunny also posted a +16% gain in Men 18-34 (1.01 million) and an +11% increase in Men 18-49 (1.24 million) vs. season five premiere, also all-time series highs. The 2.21 million Total Viewers was off -1%, but will no doubt register as a series best when Live+7 data is factored in. Compared to its complete season five average, last night’s season six premiere registered increases of +31% in Adults 18-34, +29% in Adults 18-49, and +24% in Total Viewers.

Last night’s season two premiere of The League (10:30 PM, 9/16) had an excellent night, posting series highs every category. Compared to its season one debut, The League recorded increases of +76% in Adults 18-49 (1.38 million), +63% in Adults 18-34 (994,000) and +72% in Total Viewers (1.71 million), as well as +79% in Women 18-49 (379,000) and +78% in Men 18-49 (1.0 million). The League retained 77% of It’s Always Sunny in Philadelphia’s lead-in Total Viewers and 76% of Sunny’s Adults 18-49 audience, topping the 62% average retention of last year’s Sunny lead-in audience (six weeks). The League ranked #3 in cable for the night in delivery of Men-18-49 and Men 18-34, and beat all broadcast programs in those demos at 10:30. Compared to its complete first season averages, last night’s episode of The League registered gains of +58% in Adults 18-49, +46% in Adults 18-34, and +58% in Total Viewers.

Source: The Nielsen Company (Live+Same Day, 9/16/10)

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