One out of seven Americans who go online use Twitter and eight percent do it every day, a survey showed Thursday.
The survey by the Pew Research Center found the number of Twitter users has doubled in the past two years to 15 percent of online adults.
It found that those who use Twitter on a typical day has doubled since May 2011 and has quadrupled since late 2010, probably due to the growing use of smartphones.
Twitter, which allows its members to post brief comments, links or pictures, claims to have more than 140 million active users, with the largest number being in the United States.
The Pew survey found usage is driven by the 18-24 age group, 31 percent of whom use Twitter. African-Americans are also active, with 28 percent using Twitter.
Nine percent of cell phone owners in the survey said they used the device for Twitter, but the proportion in the 18-24 age group was higher at 22 percent.
The survey found 16 percent of smartphone owners use Twitter on their phones, and 10 percent do so on a typical day.
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