Nice post. It is always interesting to follow this kind of data.
I don't understand why everyone is still worrying about the price of STEEM so much. Unless people are speculating on the price it doesn't really matter that much.
A lower price actually makes it better for adoption and distribution and makes it easier for new people to power up.
The whole SBD/dollar peg ensures that payouts don't actually fall in value and the amount of SP that people gain goes up when the Steem value goes down. The whole system is designed to keep the Steem price low and these issues are discussed in the whitepaper.
I suspect the trend in falling votes and comments is due to a lot more new people being attracted by the idea of making a quick buck and doing a "run and gun" type of post where they just post and leave.
There may also be a long term trend with people not really feeling that they get much of a reward out of curation. This may partly be down to voting at the wrong time or on big money posts when the rewards are likely to be a lot less than they would be for curating new and unique posts.
Most people don't seem to be informed or interested in reading up on the basics of how all this works so it should perhaps not be all that surprising.
Either way we need to find ways to make curation and commenting more attractive to people.
Other than raising curation rewards or limiting posting without curation I can't really think of a way to do this.
Perhaps other people have suggestions?
When the $ value of STEEM falls, so do payout amounts. Rewards are essentially a fixed amount of STEEM, some of which is converted to SBD. So we'll be seeing dramatically lower payouts in the coming week as the STEEM bubble deflates, I suspect.