June 1, 2012 at 1:57 PM ET
The number of online American adults who use Twitter on a typical day has doubled since last May, according to a new report about the short-messaging site.
"Some 15 percent of online adults use Twitter as of February 2012, and 8 percent do so on a typical day," Pew Research Center's Internet & American Life Project said in the report.
While the 15 percent figure is "similar to the 13 percent of such adults who (said they used Twitter) ... in May 2011," the actual "proportion of online adults who use Twitter on a typical day has doubled" since last May, and "quadrupled since late 2010," Pew said.
"At that point just 2 percent of online adults used Twitter on a typical day," the research organization said. "The rise of smartphones might account for some of the uptick in usage because smartphone users are particularly likely to be using Twitter."
"I do think it's notable that typical day Twitter usage is growing even as the overall usage stats have remained fairly consistent," Aaron Smith, Pew senior research specialist, told msnbc.com. That "would imply that existing Twitter users are growing more engaged over time, with mobile being a big part of that story," he said.
Twitter's users are also trending young: Pew found that 31 percent of 18-to-24-year-olds use Twitter. Among those in the 18-to-29-year-old age range, 26 percent use Twitter, "nearly double the rate of those who are ages 30 to 49."
Twitter is estimated to have nearly 600 million registered users worldwide, compared to Facebook's 900-million-plus-and-closing-in-on-1-billion figure.