Just 3% of the Facebook News Feed is made up of ads, according to a study from social media marketing management company Socialbakers.

That may seem surprising to some users who might assume their News Feeds are stuffed with promotional posts, and the fact that Facebook generated $11.5 billion in advertising revenue last year, but the study found that very few of the posts they see in the feed when they are browsing on their desktops have been paid for. But the scale of Facebook means it doesn't necessarily have to increase its ad load within the News Feed any higher (as it is often asked about by analysts) in order to keep ad revenue rolling in.

The research didn't account for mobile ads (the majority of visits to Facebook are on mobile,) or Facebook's "right-hand rail" ads, however.Socialbakers also found that 24% to 29% of the typical News Feed is made up of content from Pages - owned by companies, celebrities, public figures, and organizations. The fewer Pages a user likes, the higher share of sponsored Page posts they will see. Some 10% of Page posts are sponsored overall (but 97% of the content users actually see in their News Feeds is organic, not sponsored.)

Back in 2013, Socialbakers found that Pages owned by brands were receiving more interactions (likes, shares, and comments,) but now content from media and publishers' Pages receive around three times more interactions compared with brand Pages.

Socialbakers also looked at the order of posts in the News Feed, and uncovered some interesting insights as to how Facebook's ranking algorithm works. The company found that if the second post on your News Feed is a Page post, there's a 46% chance it was promoted. Later on in the feed, around one in every five posts is from a Page. And video posts from Pages seem to be equally spread, no matter how far a user scrolls down through the feed.

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Socialbakers' study was based on activity from 900 users on more than 23,000 Facebook sessions.