VENTUREBEAT — December 2009 data from comScore puts Facebook’s unique US visitor count at nearly 112 million. With a total estimated US Internet population of 205 million, that means that 54% of all Internet users are on Facebook. MySpace captured a still strong 57 million users in December -- 27% of the Internet population. Social Networking by the Numbers, a study I conducted using comScore and Experian Hitwise data from December 2009, details US data on visitor counts, time spent, and growth rates for the top 10 purely social networks (not vertical networks like LinkedIn and Flixster) over the past year. Click here for the complete article and presentation. Some surprises in the comScore data...