Can you verify your calculations?
Of course.
Look at
block 4500 on the block explorer. (The last Proof Of Work block)
Outstanding coins = 913,277.500272311Deduct the Outstanding Coins value above from that of the current block. Using
block 21588 at the time I type this:
Outstanding coins = 913,595.438148831913,595.438148831 - 913,277.500272311 = 317.93787652
Block 4500 was created at 4:19 am (GMT) on 18th July that's currently ~2 hours short of 16 days.
317.93787652 / 16 = 19.8711172825
20% interests per annum is not equivalent to 316 coins in 16 or 17 days (I assumed daily compounding of interests).
You're also assuming everyone is staking.
Bittrex holds ~47% of all coins and most of their wallet addresses seem to be flagged as belonging to them. I don't think I've ever seen one of those flagged addresses staking.
The amount of the coins that are generated by staking at each block doesn't (directly) depend on the number of addresses that are staking.
Function GetProofOfStakeReward depends on the coin age (probably age of the coins in the user's wallet) and doesn't depend on the total number of coins (or addresses) that are staking.
The last published binaries (compiled by the devs) weren't compiled from the source code at
https://bitbucket.org/keycoin/keycoin/and so they may contain some undisclosed changes compared to bitbucket source code (but it is probably unlikely that these undisclosed changes are related to PoS).