The number of people visiting social networks continues to rise, but the rate at which these visitors return to sites like MySpace and Facebook is on the decline. According to ComScore, the average visits per visitor to MySpace are down 11.6 percent year-over-year. To Facebook they're down 12.3 percent. To social networks in general, they're down 1.8 percent. The numbers suggest social networks aren't as crucial to their users' lives anymore. And they've never been critical to advertisers. As few as 4 in 10,000 people who see ads on social networking sites click on them. As good a time as any for Rupert Murdoch to dump MySpace in Jerry Yang's lap.

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