Cable TV networks are ending the summer with a number of big successes -- surprisingly with scripted TV shows, while no broadcast show introduced during the summer months has made it, USA Today indicated today (Thursday). (On Wednesday, Fox's newest entrant, Buried Treasure , became the latest broadcast reality show to be buried in the ratings.) Summer is "a mirror image of what happens during the regular TV season," Sam Armando of Chicago ad buyer SMGx told the newspaper. "The networks heavily rely on reality shows," while top cable channels "heavily rely on scripted programming." Some of the biggest cable hits included MTV's Jersey Shore with 8.6 million viewers; TNT's Rizzoli & Isles, with 8.1 million; TNT's The Closer with 7.9 million; History Channel's Pawn Stars with 7.3 million; and TNT's Falling Skies with 6.9 million. By contrast, no new show introduced by a broadcast network drew as many viewers, despite the fact that broadcast viewership in general far exceeds cable. Ratings for the broadcast networks have fallen 2 percent this summer versus last year, while some cable ratings have soared, USA Today observed. History Channel is up 41 percent and FX, 20 percent. Although there have been some significant cable channel downturns as well. Nick at Nite is down 23 percent and TBS, 21 percent.