As Facebook reached 350 million users worldwide, its largest single source of growth in December 2009 was still the U.S. Inside Facebook reported that the US gain of more than 4.5 million monthly active Facebook users was the highest number of any country. Because of the large installed base of US Facebook users, it represented a 5% gain, compared with 10% growth in countries such as Indonesia, the Philippines and Malaysia. This puts Facebook’s U.S. monthly active user audience over the 100 million mark.
The largest gain came from males ages 18 to 25, followed by women 26 to 34. Despite the already-large base of users under 35, those groups also posted the highest rates of growth. Increases in usage among older users, which was relatively stronger earlier in 2009, had slowed.