The comScore figures only count traffic to Twitter.com and not the traffic to Twitter apps, such as TweetDeck and mobile app Tweetie, which many members use to log into the site.
During July, Twitter revealed a homepage redesign which highlights the site's search feature along with the trending topics. The site also launched a beginner's course for clueless brands and marketers called Twitter 101 in July.
ComScore also provided the statistic that 11 per cent of Twitter's users are aged 12 to 17.
Nielsen research earlier this month claimed that only 16 per cent of Twitter's users are aged under 25.
According to one theory, teens are more interested in Facebook than Twitter because their lives tend to revolve around their friends and Facebook is more oriented around friend groups.
Twitter however is better for broadcasting comment, ideas or products to the outside world, to people users have never met.
Evan Williams, Twitter's co-founder and chief executive, said: "Many people use [Twitter] for professional purposes -- keeping connected with industry contacts and following news.
"Because it's a one-to-many network and most of the content is public, it works for this better than a social network that's optimised for friend communication."