"Another way in which you as a content creator can dominate the search rankings with your content is to get more and more social shares.
A study by branded3 proved the connection between tweets to a particular URL and its ranking. Their results showed:
1) 50 tweets or less – Not sure how much, but URLs received benefit in rankings with 50 tweets or less, but those benefits declined after that.
2) 5,000 tweets – There’s a huge jump for a page that gets an average of 5,000 tweets. This would be content that goes viral on Mashable, BuzzFeed or Copyblogger.
3) 7,500 tweets – When a page gets 7,500 or more tweets, they can easily show up in the top five SERPs on Google".
Via Antonino Militello