In a new study published today, Pew examines the demographics of social media users in 2012. A few takeaways: The percentage of Internet users on Twitter has doubled since November 2010, women are about five times as likely to be on Pinterest than men, urban residents are much more likely to use Instagram than suburban or rural residents, only 6% of all Internet users use Tumblr, and Facebook is still crazy popular among pretty much every age, sex, race, and income bracket. [Source: Pew]