RivalIQ published findings from a study of 8.1 million Facebook posts from brand pages that saw 11.5 billion interactions (likes, comments, and shares).

Brand pages grew 27.8% from February through December 2015, or an average of 2.26% per month, it found. The largest pages saw the least amount of growth while the smallest saw the most. The study shows a dip in growth in March 2015 due to changes Facebook announced that changed the way page likes are counted. Over the course of the year, however, the study shows consistent growth for pages, though it’s fairly slow growth. This, the firm says, is a sign that Facebook is a “mature platform,” offering consistency and predictable performance.

The study found that the bigger the page audience is, the more posts are coming from those pages. For every 10x increase in page fans, they saw an increase of 0.4 posts per day. Pages with under 6,000 fans posted about 12 times per month while pages with over a million fans posted about 46 times per month (which still seems low if you ask me). Interestingly, engagement rate per post falls as pages get larger. This chart from the study looks at average engagement rate per post, average audience size, and average total engagement per post plotted against posts per day.

“You can see that engagement by audience is consistent but the total engagement drops,” the report says. “In short, posting volume is what drives down engagement rate per post, not just page size. The takeaway is that each extra post per day gets incremental engagement, but with diminishing returns. Those returns vary by audience size, with larger pages generally having smaller per-post engagement rates. Said differently, it can be worth it to post more frequently. But, don’t expect to maintain your engagement rate on a per-post basis.”

Of course the type of page likely plays a significant role in this. Here’s a look at posts per day by category. Media pages post more frequently than other non-media categories, unsurprisingly.

Overall, the study found that bigger pages, on average, have a smaller engagement rate per post (0.22% for smaller pages and 0.06% for larger pages).

It also found that likes and comments are down while shares are up. It posits that Facebook algorithm changes contributed to this as well as marketers getting better at learning what users want to share, an iOS sharing extension, new sharing features in messenger, and the way Facebook displays shared posts in the News Feed, which encourages mores sharing.

The study found that shares occur more than twice as frequently as comments on an average per post basis. The average post gets 83.4% of interactions in the form of likes while 11.2% come from shares and 5.4% from comments.

The picture is fairly consistent across audience sizes:

“Engagement in the form of likes and comments did decrease in 2015, but it was up in regards to shares. The cause for both the decline in likes and comments and the increase in shares likely has to do with Facebook’s ever-changing newsfeed algorithms,” the report concludes. “Additionally, fans are twice as likely to share a brand’s content than comment on it. But, likes were still likely to account for over 80% of all engagement. Though the like/comment/share ratio was consistent across audience sizes, these ratios vary depending on page category.”

Our summary of RivalIQ’s findings here is really just the tip of the ice berg. Check out the full report (via Marketing Land) for lots more data and analysis of brand performance on Facebook.

Images via Facebook, RivalIQ