Social Networks: 57.5% of Internet users…
.. in the US, will use a social network at least once a month in 2010, estimates a new marketing report by Emarketer.
By 2014, nearly two-thirds of all Internet users [in the US], or 164.9 million people, will be regular users of social networks.
Williamson,Debra Aho. Social Network Demographics and usage. Emarketer report: May 2010. 26 p.