https://phys.org/news/2018-06-hackers-30m-seoul-bitcoin-exchange.html

Hyper-wired South Korea has emerged as a hotbed of trading in virtual units, at one point accounting for some 20 percent of global bitcoin transactions—about 10 times the country's share of the global economy.

Bithumb, which has more than 1 million customers, is the largest virtual currency exchange in the South.