Thanks for the link!
However, the 4-month gap in the OKCoin data (Feb to May) is inexcusable, and invalidates some of their comments. Bitcoinwisdom has got the OKCoin volume throughout that period, and it was in fact 15-25% higher than Huobi's. Moreover, there are/were other exchanges in China besides those 3. And MtGOX, not included in that aanalysis, had significant volume through the November rally.