Bitcoin has been in a bull market like few the world has ever seen.

At the beginning of the year, the price of a Bitcoin was below $1,000. It hit $5,000 in October, then doubled by late November. And on Thursday, less than two weeks later, the price of a single Bitcoin rose above $20,000 on some exchanges, according to Coinmarketcap.
https://www.nytimes.com/2017/12/07/technology/bitcoin-price-rise.html