How many Online Americans use Twitter

According to a research conducted by Pew Internet & American Life Project in December,

11% of online Americans are using Twitter, a micro-blogging service. This comes out to be one in every Nine Online Americans.

The previous percentages were:

Now: ____________________11 %
November: ________________9%
May 2008:_________________6%

Current Growth over May 2008:_____ 83.3 %

An interesting bit about the Age profile of Twitter users in America:

One in five online Americans (20%) is in the 18-to-24 age group.
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