Social media marketing is getting even bigger than before and now the percentage of Americans who have profiles on one more social networking site has reach almost half (48%) of the population in 2010, which is doubled from two years ago, according to Arbitron and Edison Research.

The study has shown that using social networking sites is not just for teens. 65 percent, of the 48 percent of the popular, are those 25 to 34 and half of those numbers are 35 to 44.

“The use of social networking sites has expanded beyond younger consumers, with substantial numbers of Americans over the age of 35 now using social media,” said Bill Rose, Senior Vice President of Marketing, Arbitron Inc.