Japanese forums have been raided by Chinese trolls in the past. Now the Japanese just post a statement about Tienanmen square and poof, no more Chinese attendance, as the Great Firewall starts blocking...
Currently BTC.COM and AntPool combined make up 42.5% of the network and both are both owned by Bitmain, a company headquartered in Beijing.
ViaBTC is also a Chinese mining company operating out of Shenzhen and has 10.1%. I'm not going to bother checking the rest since that's already 52.6% of the network controlled by 2 companies under 1 authoritarian regime.