Well done, I think the data shows that the real decline in payouts has obviously come from the decline in the Steem price. I'd also wager that the decline of comments and increase in upvotes is largely due to bot activity.

Since we have an increase in posts and decrease in comments another possibility could be that the post quality is in decline and not engaging enough to be worthy of commenting on.

This was a great post! Thanks for taking the time to put it all together and crunch the numbers. Definitely worth an upvote, comment and resteem.