Facebook remains the most popular social network platform for U.S. Internet users whereas Twitter has failed to attract more users since last September, a study showed Wednesday.

According to the Pew Research Center report, 72 percent of online American adults are currently using Facebook, a proportion barely changed from September 2014.

The report found that Facebook is especially popular among online women, 77 percent of whom are users.

Demographically speaking, younger population is also more inclined to use Facebook, a finding consistent with the past research. According to the Pew report, 82 percent of online adults between the age of 18 and 29 use Facebook.

While popularity of Facebook has not dipped in face of a wider range of other social networking tools, such as Pinterest which enjoys 31 percent of online usage and Instagram which boasts 28 percent of online usage, Twitter has failed to keep apace with its rivals in terms of attracting Internet users.

According to the report, some 23 percent of all online adults use Twitter, a proportion identical to that in September 2014.

Compared with the elderly, young Americans are more likely to use Twitter, said the report. However, the popularity of Twitter among younger adults is far lower than that of Facebook. Only 32 percent of online adults between the age of 18 and 29 use Twitter.

Meanwhile, unlike Facebook, 70 percent of whose users use the site on a daily basis, Twitter also has difficulty in luring its users back more frequently. Only 38 percent of Twitter users report visiting the site every day.

The Pew report is based on telephone interviews conducted from March 17 through April 12 among a national sample of 1,907 adults.