Data released Thursday shows that social sites drive the most traffic to websites, but search engines drive the most conversions.

The data from Heap, a mobile and web analytics company, seems to contradict historic views on the type of companies driving traffic to websites.

For Facebook, Heap analyzed the data of 25 large ecommerce companies with a data set around visitor-to-purchase conversions rates on the websites of 25 ecommerce companies. For a given company in the dataset, Heap looked at the total number of unique visitors in one week and the percentage of those visitors who also made a purchase.

Search engines like Google and Bing had the highest customer conversion rates — about 8%, more than 1.5 times higher than Facebook’s. Google topped the list of highest conversion rates with 8.2%, followed by Bing with 7.6%.

Facebook converted traffic at 4.7%. Instagram came in at 3.1%, and Pinterest at 2.9%, while Twitter’s rate was less than 1% and Snapchat took 0.60%. YouTube drove an average conversion rate of 0.50% during the study.

The conversion rate varies quite a bit within each advertising source. While Google had the highest conversion rate, analyzing the spread of scores the data shows Bing and Facebook each separately outperform Google when it comes to some websites.

The overall trend of social driving traffic and search engines driving conversions, however, sticks when analyzing the spread of scores, according to Heap. Generally, Google, Bing and Facebook will drive higher conversion rates, per the data.

Less websites use Snapchat, Twitter, and YouTube. Heap suggests this may be “because it is hard to monetize these sources.”

When it comes to driving traffic to websites, Facebook and Snapchat drove the most. Facebook drove 13.9% and Snapchat drove 13%.

Facebook drove about 21.73% of traffic to ecommerce websites between March 11, and March 17, 2018, falling to 17.45% between March 18 and 24, 2018, and 14.25% between March 25 and 28, 2018.

Google comes in at a close third — driving 9% of traffic, with a sharp drop in traffic from the rest of the referral sites. Twitter drives about 0.3% of traffic to websites. YouTube follows with 1.2%, and Bing comes in at 2%.