Below are the most searched terms at Google China for 2007 according to a Reuters article on cnet and another story from China Daily. The term "sex" was not in the top ten.
news.com/Stock-beats-sex-on-Go ...
chinadaily.com.cn/china/2008-0 ...

1. QQ (an instant messaging service and a car)
2. China Merchants Bank
3. the Industrial and Commercial Bank of China
4. stock
5. game
6. China Construction Bank
7. Google Earth
8. Thunder (a download tool)
9. Kaspersky (malware detection)
10. MSN

Capitalism seems to be a major interest in a communist country.
Over population is often a concern in China, but a low priority seems to be placed on seeking information about sex.