Washington, D.C.—Although two-thirds of U.S. adults are Facebook users, 61% of them have taken a break from using the social site for several weeks or more, according to a report from the Pew Research Center. According to Pew's "Coming and Going on Facebook" report, 21% of respondents said that their “Facebook vacation” was a result of being too busy with other demands or not having time to spend on the site. Others pointed toward a general lack of interest in the site itself or concerns that they were spending too much time on the site and needed to take a break. Also, 20% of the online adults who do not currently use Facebook said they once used the site but no longer do so. The report was based on telephone interviews with 1,006 U.S. adults, conducted in December.