ShareThis have released their analytics data to throw some insights into what the visitors are sharing in the internet.
From the chart released by ShareThis, it's obivious that the Entertainment, Science & Technology blogs uses more of the ShareThis widget to post the content to the social networks. And this indirectly implies that these sites are the one which are shared the most on the site.
So if you assume ( blindly ) that the ShareThis widget is used all over internet in all blogs, then Entertainment , Science & Technology occupies much space in the internet. Though it is not very sensible to conclude this, but this graph is intresting enough to visualize what kind of sites occupies the internet.