but i have no reason to lie about it.

It could be that more people say it but censor themselves around people who they assume don't. White people ostracize and shame other white people who say it so I suppose it's possible that people 'save it' for when they're around like-minded racists or something like that. But I'll say this....it is by FAR the most stigmatized word in language, even amongst white people in groups. Way more than any other slur, be it gender, race or orientation. 1 in 20 is generous in my experience.