Most of the miners are in China .
Price is Very Cheaper ( Manpower, Electricity, Goods, Etc... ) and they have Universal Marketing, and also the mining hardware companies are domiciled in China.
More and More Incomes and Sources in china.BTC
^this guy forgets about georgia,mongolia, etc and other countries^
take slushpool
china ~8peta
europe ~80peta
america ~115peta
https://slushpool.com/stats/?c=btc