American Internet users, 8% using Twitter.

Research Center Pew Research Center surveyed 2,257 U.S. Internet users that people "use Twitter or not, the answer is 8% said that they were using Twitter on a regular basis.
If you think by population. The following interesting information.

    * Age group 18-29 years with most Twitter is 14%.
    * 10% more men than women use to 7%.
    * Hispanic groups (Hispanic) used 18% and the African - American, 13% higher than white people to use just 5% with significance.
    * Urban than rural people to use a double (11% to 5%).
Source - Blognone, Pew Research Center.