Social networks are sending nearly 13% more traffic to online retailers this year than in 2009. A new Hitwise report shows that social networking sites accounted for 11.6% of all UK Internet visits during September, representing a year on year growth of 4.3%.

Facebook accounts for 55% of all visits to social networking sites, making it by far the biggest social network in the UK. It is also the second biggest source of traffic to all websites after Google. Approximately 1 in 10 visits to a website in September came immediately after a visit to Facebook, up from 1 in 13 visits back in September 2009.

Online retailers are increasingly relying on traffic from social media to drive sales and interest in their products. In September 2010, 9.1% of visits to the Shopping and Classifieds category came from social media, up from 8.3% in September 2009.

See Hitwise for full report.