Bitcoin total supply is 21 million coins and there is less than 2,6 million left to be mined.
Almost 88% of all Bitcoins have been issued so far.
I like visual representations, and I found one for Bitcoin supply.
1 square equals 1000 BTC, and there are other categories like:
Lost Coins, Coins on exchanges, BTC/Year after halving, Grayscale Bitcoin Trust, Plus Token Scam, Mt Gox Wallets, Winklevoss Twins, Bitfinex Hack, Roger Ver, Tim Draper, Bitcoin Pizza, Lightning Network and Rest.
Each category has it's own color and reference link.
You can see that nice chunk of coins is kept on exchanges (sadly)
source:
https://www.blockchaincenter.net/bitcoin-supply/As far as the amount of bitcoins actually minted in circulation, the Bitcoin network has recently passed over the 18.5 million level. However, while more than 18 million coins have been minted to date, there are a range of distinct elements that influence the distribution of all current coins. Large holders, missing coins, so-called sleeping coins, and coins kept in custody for multiple solutions are elements that influence bitcoin distribution.
The outstanding circulating BTC supply is about 18,508,600 BTC as of today, although several individuals have been debating the actual distribution of the circulating supply over the past 12 months. For instance, news.Bitcoin.com reported on an analyst in mid-September who said only 14 million out of the 21 million supply limit would ever circulate.
Coin Metrics also conducted an article last year, discussing a number of approaches to determine the true supply of Bitcoin. At that time, Coin Metric's estimate of the "liquid" availability of BTC was about 16.3 million as of block height 600,000.