Sunday’s second season premiere of The Walking Dead delivered monstrous ratings for AMC: 7.3 million zombie lovers tuned in, shattering all previous records for the show and dramatically improving on last year’s series premiere tune-in of 5.3 million. The story was even better for AMC in the key demo of adults 18 to 49, where the show averaged 4.8 million viewers under 50 and scored a 3.8 rating — bigger than just about everything else on network TV Sunday, save for NFL football. AMC programming chief Charlie Collier, who’s taken a beating in the media for various behind-the-scenes dramas at the network, clearly is giddy about the numbers, given this awesome statement he issued about the show’s ratings. Said he: “That The Walking Dead is now the most watched drama in the history of basic cable is staggering, just like our zombies.â€