The number of new social networking site users has grown by 25% in the last year, according to a report released Tuesday.

ComScore, an online metrics company, reported that global use of social networking sites has risen as growth among new North American users has slowed slightly to 9%.

"While the social networking trend first took off in North America, it is beginning to reach a point of maturity in the region," Jack Flanagan, ComScore's executive VP, said in a statement. "However, the phenomenon is still growing rapidly in other regions around the world -- especially as the established American brands turn their focus to developing markets."

The number of new users in the Middle East and Africa has risen by 66%, while the number of new users in Europe rose 35%. In Latin America, the number of new users on social networking sites rose by 33%.

Facebook.com has held the top spot among social networking sites worldwide since April 2008. The site experienced 153% growth in the past year, due in part to its use of natural language interfaces, ComScore reported. Most of Facebook's visitors (49 million) still come from North America, although Europe appears to be catching up, with 35 million users. Growth in North America stood at 38%, while European users grew by 303% and worldwide users quadrupled, according to ComScore.

"Facebook has done an exceptional job of leveraging its brand internationally during the past year," Flanagan said. "By increasing the site’s relevance to local markets through local language interface translation, the site is now competing strongly or even capturing the lead in several markets where it had a relatively minor presence just a year ago." Hi5.com has doubled its number of visitors to over 56 million, and ComScore credits the site's strategy to localize. Friendster.com users are up 50%, while Orkut users grew by 41%, and Bebo users increased by 32%, according to the report.

MySpace still holds the No. 2 spot, but its global year-over-year growth among users reached just 3%.

InformationWeek recently did a report on how businesses are using social networking sites to improve employee communications and collaboration. You can download the report here (registration required).