BTC China volume 
Where is Huobi?
In terms of volume for Chinese exchanges, it's OKCoin, then BTCChina, and then Huobi. Where is Huobi? I believe they are getting their OKCoin volume purely from the international market spot exchange, which is the lowest volume of all 6 of OKCoin's BTC orderbooks. Their international exchange isn't even Chinese-based - it's a Singapore company and is meant to serve customers in every country.
If they're including Bitfinex, they need to include 796 and OKCoin futures markets.
Since when is Bittrex considered a Bitcoin exchange? They only trade altcoins.
This infographic is a joke. Whoever made it is clueless and doesn't actually know anything about any of these exchanges, besides maybe Bitstamp. 