When it comes to referral traffic from social networks, there's Facebook and Pinterest — and then there's everyone else.

Facebook accounted for more than 10% of overall traffic to publishers in September, by far the most of any social network, according to data released Tuesday from Shareaholic, a social plugin service that collects data from 200,000 publishers reaching 250 million monthly unique visitors collectively.

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Pinterest drove 3.68% of traffic to publishers in September, the second highest of the social networks on the list and three times as much as Twitter, which ranked third. In fact, Pinterest's share of overall visits increased by 66% year-over-year, more than any other social network. Pinterest now drives more traffic to publishers than Twitter, LinkedIn, Reddit and Google+ combined.

While most of the social networks tracked in the study showed significant year-over-year gains in referring traffic to publishers, referral traffic from Reddit and StumbleUpon declined 35% and 27.5%, respectively. Google+ remained essentially stagnant year-over-year and continues to refer the least traffic to publishers of the major social networks included in the study.

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