Says a study by Socialbakers. Since the same research says that 75% of all posts were photos, they seem to perform significantly better than other other posts, like links for example - if performance is measured by shares. The interesting thing is that in January 2014, photos made up "just" 54% of Facebook posts.
Visual is the new black, obviously.
Similar study from March by Quintly (incl. 43 slide presentation embedded)