The Washington Post: A new report from comScore shows that Facebook's audience and time spent on the site are growing more slowly than previously. In April, Facebook's unique visitors were 5 percent higher than in the year previous, but in April 2011, unique visitors climbed 24 percent. Similarly, in 2012 time spent on the site grew 16 percent, compared to 23 percent in 2011. The slower growth was “expected given Facebook’s current size and market penetration,” noted comScore's Andrew Lipsman.
Currently, Facebook has 900 million members worldwide. In North America, 70 percent of Internet users have Facebook accounts.