I doubt it. Blocking an entire country seems a bit of overkill to me but ... the first place I'd look for any such information would be www.apnic.net who indicate that China holds in excess of four /8 blocks worth of IP's. That's over 4 class A's or in excess of 66 million IP addresses.
We have all china blocked, and this reduced hack attempts and spam with over 50%. Ofcourse if a user indicated he wants Chinese visitors or if they indicated he wants to be able to see Chinese website we can enable this for this specific server/ADSL connection.