Zynga made up 12% of Facebook's revenue in 2011

Revenues from Zynga games accounted for 12 percent of Facebook’s 2011 revenues, the social network’s S-1 filing reveals. No other customer represented more than 10 percent of total revenue in 2009 or 2010. Facebook reports that social game devs — most of all Zynga — are currently responsible for almost all revenue derived from Payments.