Report: Social Networking – Coming and Going on Facebook, by Lee Rainie, Aaron Smith, Maeve Duggan, Feb 5, 2013. “Two-thirds of online American adults (67%) are Facebook users, making Facebook the dominant social networking site in this country. And new findings from the Pew Research Center’s Internet & American Life Project indicate there is considerable fluidity in the Facebook user population:

• 61% of current Facebook users say that at one time or another in the past they have voluntarily taken a break from using Facebook for a period of several weeks or more.
• 20% of the online adults who do not currently use Facebook say they once used the site but no longer do so.
• 8% of online adults who do not currently use Facebook are interested in becoming Facebook users in the future.”