Even with the raised fee, people are still trading at OkCoin and BTCC with huge volume compared to other exchanges.
I don't find huobi in your second pie chart, is there any reason for that?
the Chinese have always been good "traders", no matter what they trade. in different things. and when bitcoin was introduced they rushed to exchanges to make more money and when altcoins came they gladly added the top couple of them to their exchanges to make more money. and because of this, they will always have higher volume. and besides the population of China alone gives them higher volume compared to other countries.
unlike d5000 above i don't expect volume go much lower than this in long term, since it is about the same as bitfinex,... volume now.
and d5000 is correct about the API problem.