You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract AddThis: Facebook Makes Up 52% of Sharing on the Web A Look at Top Social-Sharing Trends of 2011, From the Leading Sharing Platform By Simon Dumenco, Published on December 13, 2011 4 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.