The total circulating bitcoin supply reached 18.899 million as of December 13, making it 90% of the maximum limit, and the rest is expected to take more time.
The first mining phase has taken 12 years, delayed by the halving process, which happened one and a half years ago.
The hard cap of the primary cryptocurrency was set at 21 million by its founder, Satoshi Nakamoto, and is captured in the source code. The maximum limit is implemented by the blockchain nodes.
It would take 119 years from the present to complete the mining of the remaining supply. The production rate of new tokens is reduced by half every four years.
Bitcoin miners have been receiving 6.25 BTC for each block, and the rate is expected to drop to 3.125 in the following halving, set for 2024. The last BTC would take about 40 years to be mined.