I am assuming that you are interested in how Western parents deal with their children and homework. I haven't been able to find a systematic study of this so I can't provide you with definitive figures. My guess is that there is wide variation among parents in the West regarding how much studying they try to get their children to do.

I know that my parents expected me to do my homework and stay on top of my studies. Most parents want their children to do well in life and many of them value education. I think that the amount that parents value education is probably the biggest factor how much studying they want their children to do.

Perhaps you are really more interested in the cultural differences between the West and China in how parents approach their children's homework. To help give you a better understanding of Western thinking on children and homework I am going to give you some links to articles on the Internet giving parents advice about how to support their kids in doing homework. These may give you some insights into Western Culture.

Homework: A Guide for Parents

How to Make Your Kids Do Homework

Tips for Helping Kids and Teens with Homework and Study Habits