While the amount of people using the #1 social network in the world continued to increase last year, the demographics of the users changed slightly. Facebook users remain split between generations.
In 2009, the number of Twitter users increased by 900%, from just 2 million users in 2008, to over 20 million users by the end of 2009. The Twitter user demographic that increased most rapidly in the past year is the 18-24 year old set. This shift results in a fairly even split between Twitter users who are over and under the age of 35.
Source: Jamiepappas.com, Comscore 2009 US Digital Year in Review