What goes up must come down. There is no series whose ratings have kept growing indefinitely, and even MTV’s mega hit Jersey Shore is not immune from that, posting its first season-to-season decline in its finale last night. The closer of the Jersey gang’s Italian adventure drew 6.6 million viewers, reversing the upward trend of 4.8 million for the Season 1 finale, 6.1 million for Season 2 and 7.6 million for Season 3. The finale was also down from the fourth-season premiere, which drew some 8.8 million viewers, the most ever for an MTV series debut. Jersey Shore‘s demo ratings are still very potent. Last night’s finale posted a 3.7 rating in adults 18-49, beating everything on broadcast TV besides CBS’ The Big Bang Theory and Fox’s coverage of the World Series.