The chart below, made by Statista from Shareaholic research, shows Facebook is king of the traffic referrals among Shareaholic's user base.
Pinterest comes in second, way out in front of much older Twitter.
The Shareaholic article covers the rest of the pack too- StumbleUpon and Reddit decline in referrals, YouTube and LinkedIn gain share at a decent clip.
Google+ is stomped by the competition, basically flatlined on the graph. However, there's a lively discussion in the article comments, about why marketers still can't afford to ignore Google+. We found this article by Mike Allton important reading, especially the quote below.
But we still believe what Dorie Clark said in Forbes last year: "No One in Marketing Knows What They're Doing". We say make good, Hummingbird-friendly content, even though you never wanted to be a publisher, and stay alert.