The second season finale of pop culture phenom Downton Abbey averaged 5.4 million viewers on Sunday, PBS’ largest audience since the premiere of Ken Burns’ documentary National Parks in September 2009. Vs. its first season, Downton was up 25%, doubling pubcaster’s primetime average. The growth was most dramatic in young demos, 251% among women 18-34, 145% among women 35-49, 111% among men 18-34 and 84% among men 35-49 vs. the Masterpiece 2010-11 season average.”Downton Abbey has become a cultural phenomenon,” Masterpiece executive producer Rebecca Eaton said. “It is so gratifying to see our beloved Masterpiece, after more than 40 years on PBS, attracting a whole new audience.”