More than a third of homes with TVs also have DVRs now, which is causing ever-larger shifts in ratings between live viewing and the "live plus 7" numbers that Nielsen gathers to show how many people watch a show within a week of its initial airing.

In some cases, it's the rich getting richer: The "Grey's Anatomy" season premiere added close to 3 million viewers, more than any other show in the week of Sept. 21. "The Mentalist," "House" and "CSI" all added more than 2 million viewers. But shows farther down the ratings, like "Dollhouse" and "Fringe," grew their ratings by the largest percentage from their initial airing.

Take a look at the shows that grew by 20 percent or more with DVR usage during the week of Sept. 21.

-- Rick Porter, Zap2it

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DVRs make the rich (and poor) richer