This is not addressed in Bitcoin's Whitepaper, although Satoshi
Nakamoto briefly mentions the decrease of the reward, but never
explicitly talks about the amount of the reward.
Satoshi speak about the halving process since the release notes for Bitcoin v0.1 Alpha:
Total circulation will be 21,000,000 coins. It'll be distributed
to network nodes when they ...
Inflation is newly mined coins added to circulating supply. When block rewards become zero and transaction fees are the only incentives for miners, there won't be any new coins added to circulating supply.
According to https://www.viewbase.com/inflation (In last 24 hours):
1031 BTC mined
Circulating Supply of Bitcoin is 18,504,668 BTC
% of newly mined coins(...