A new Nielsen report points to social networking as the primary online activity today for U.S. Internet users.

According to the study “What Americans Do Online,” social networking services like Facebook and Twitter take up 22.7% of online activity, up from 15.8% last year according to data collected in June. That’s more than twice as much as the second-ranking activity—online games, at 10.2%. E-mail meanwhile fell to 8.3% from 11.5% year-over-year, and instant messaging is down 15%.

Overall, Americans spend 36% of their time communicating via social networks, blogs, personal e-mail and instant messaging. Music didn’t make the top 10.

Videos and movies grew from 2.5% to 3.9% of online activity, a 12% gain. Videos streamed passed the 10 billion milestone in June, and the average American streamed 3 hours and 15 minutes of video for the month.