73% of online American adults use social networking sites

"Some 73% of online adults now use a social networking site of some kind.1 Facebook is the dominant social networking platform in the number of users, but a striking number of users are now diversifying onto other platforms. Some 42% of online adults now use multiple social networking sites. In addition, Instagram users are nearly as likely as Facebook users to check in to the site on a daily basis. These are among the key findings on social networking site usage and adoption from a new survey from the Pew Research Center’s Internet Project."
Source:  Pew Internet & American Life Project, 30th December 2013