Shoppers are increasingly clicking from social networks to retailers’ web sites because consumers are using sites like Facebook and Pinterest to discover products, according to a new report from Experian Marketing Services.

Shoppers clicking from social networks today account for 7.7% of all traffic to retail web sites in November, the report found, up from 6.6% a year earlier. Experian says it collects data on more than 34,000 retailers’ web sites. That’s in line with similar results reported in Internet Retailer’s 2014 Social Media 500, which ranks the leaders in social commerce by the percentage of web site traffic they receive directly from social networks. The Social Media 500 found that the 500 merchants ranked in the guide received 5.1% of their site traffic from social networks in 2013, up from 3.6% a year earlier.

Social networks are driving more traffic because so many shoppers are spending so much time on them, the Experian report suggests. 58% of U.S. adults visit at least one social network in a typical week. And among consumers 18 to 35, that percentage jumps to 78%. Consumers spend 21 minutes and 35 seconds on average each time they use Facebook, slightly ahead of YouTube visitors who spend, on average, 20 minutes and 44 seconds per visit. Twitter and Pinterest visitors spend between 10 and 11 minutes per visit. And on Google Plus, consumers spend 6 minutes and 7 seconds on average.  

“Social media is becoming a significant source of traffic across the Internet as consumers increasingly use sites like Facebook, Pinterest or YouTube more as discovery platforms,” says Bill Tancer, general manager of global research, Experian Marketing Services. “Many of today’s marketers are leveraging the power of social communities to increase customer engagement and expand their brand’s reach.”

Retailers are also increasingly pointing consumers to their social network accounts in e-mails, the report says. For example, 98% of marketers display or promote Facebook in their e-mails, up from 93% a year earlier, and 91% promote Twitter, up from 88%.

The report found that Amazon.com Inc. and Wal-Mart Stores Inc. drive the most traffic to their sites from Pinterest, Facebook and YouTube. The Social Media 500, which also examines Twitter traffic, found similar results. According to the Internet Retailer guide, Amazon drove 6.4 million unique visitors from social networks in a typical month, nearly double Wal-Mart, which had the second-most unique visitors from social networks.