I would ask if being rape is the issue or women who can seek help without shame or threats more of an issue. At least in the West a raped woman can be helped to find some kind of dignity, and her rapist put to justice, not the case under Islam. Rape statistics is very tricky because consider
1. not many victims come forward.
2. Some rape cases are falsified
3. Population of a country, there are MANY people living the US as per other countries so you can't just pluck a number and compare it to a country with a smaller population
4. In Islam if you are married you cannot claim rape whereas in the West you can.
Also I would stretch things a bit I would say in the West, women usually wait to get married and are vunerable for a longer period of time than Muslim women.
Again under Islam my main argument is a married woman cannot claim rape and Muslim women marry earlier than Western women. And a Muslim woman cannot come forward easily because something tragic will happen to her. Where as in the West we encourage people to come forward to get help, which is why it could seem we have more. I mean we have freaking billboards and help lines saying if you have been raped or even touched you call the police immediately. There is no such help in Islamic countries usually punishment waiting for the woman from either the law or her family. There are many variables. Yes the West has many rapes but there is a lot more to it that because of religion =p I also find it quite ironic that Muslim women tout that wearing hijabs will prevent rape where statistically in the West most rapes occur indoors, not outdoors and close to 1/3 of them are between people who know each other not complete strangers.
Wikipedia it =p it
http://en.wikipedia.org/wiki/Rape_statistics