This site states differently and says that the age is 14, and only 16 if the man is over 21.
However, this is the internet. You're going to get mixed messages and reports all over the place. I wouldn't outright trust any site you find. If it's enough of an issue to you, go ask somebody who would know or do some of your own research at the library.
Do I think it's a stupid law? Yeah. Would I keep having sex with my girlfriend? Yeah. But would I complain when I got in legal trouble because it's technically illegal? Only because the law is ignorant of the people under it. If you decide to keep having sex with your girlfriend in spite of the law - saying, "Fuck the man" as you do, you may find yourself getting fucked right back by the man without any kind of protection.... and he looks like this:
