I'd be curiouis to see a breakdown on .cn names by language and by subdomain (.com.cn), which I think would be more comparable.
Another factor in .us is that we also have many domains in the .mil, .gov, and .edu domains (not to mention a head start on the gTLD's) which in china would be contained under .cn adding to the figures. I know of several cities and states that have moved from .us to .gov when they were finally allowed to.
{edit} Actually, I went to the link shown in the first post. and found this:
.com.cn - 343,416
.net.cn - 36,135
.org.cn - 13,984
.gov.cn - 21,437
.cn - 522,227
187,813 subdomain.cn existed before the plain .cn was opened up. The stats shown for .us is 944,288 registrations.
First, I'll bet a lot of the .cn are duplicates of the .com.cn and .net.cn (redundancy). Second, there is no .com/net/org registerable subdomain of .us, therefore the .us domain is really more like double that of ".cn". I think the title statement to this thread is probably a little off the mark. Not to mention the fact that US companies prefer .com. I don't think you can really compare raw numbers of ".us verses .cn"