The sixteen millionth bitcoin was mined in block number 440,000 on November 22, 2016. Due to the block reward of 12.5 bitcoins in this block, there are now sixteen million bitcoins in circulation. Ultimately, there will never be more than 21 million bitcoins, so more than 75% of the bitcoins have already been mined.

The first sixteen million bitcoins have been mined in about eight years, since mining began on January 3, 2009. Due to the block reward, which halves every four years, four million bitcoins will be mined over the next ten years, and it will take more than a hundred years for the last bitcoin to be mined.

Here is the full chart of the number of bitcoins in circulation.