In February 2013 Pew Research released their research on the Demographics of Social Media. Which has some interesting data such as:
77% of the average age of social media users are between 30-49
71% of women use social media versus 62% of men
The household income of top social media use is less than $30k
The ethnicity breakdown is:
Black, Non-Hispanic 68%
White, Non-Hispanic, 65%
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