According to the company, Facebook, one of the most popular social networking sites on the planet, added its 200 millionth user on April 8, 2009.

To mark the occasion, Silicon Alley Insider noted that if Facebook were a country, it would be the fifth-largest in the world after China, India, the US and Indonesia.

The US had more Facebook users than any other country. However, the largest concentration of users was in the Eastern US and Western Europe.

From January to March 2009, people ages 26 to 44 made up the fastest-growing segment of the US Facebook population, and other countries will undoubtedly follow that path.

Source: eMarketer
http://www.emarketer.com/Article.aspx?R=1007034