I am conscious of the differences of both markets. I just took the top 10 list posted by @firedeep and I did a quick comparison.
I prefer to see the films over a lower amount. For instance, $50m/320 million Yuan (I prefer to take a Yuan figure instead a dollar one given the continous change of ER) . Since 2010, US has made 66-69 films per year making those $50m. China had 5 films in 2010 over 320 million Yuan, 8 in 2011, 13 in 2012, 19 in 2013, 30 in 2014. This year, for the moment, the result is 41 vs 34.
I have no doubts that US will increase that amount towards the usual 65-70 films because of awards season. The question is which will be the Chinese number, 40?, 45? that would mean 10-15 films more than last year reaching a considerable amount. China continues growing and narrowing the gap. Obviously, there is still a big difference, but unless the market collapses (there is a certain risk given some doubts about the economy), the trend is clear.