Why do black guys always holler at me?

I'm a Latina and though I have nothing against black people, I am not attracted to them. But it seems like the only kinds of men who does hit on me are black men. I would walk down the street, minding my business and then have a black guy hit on me. I can wear the baggiest clothes (a baggy shirt and sweats) and I still get hit on by them. I actually feel degraded when black men does that. Why do they do it? What I hate the most when they say "hey ma". I ignore them but deep down it bothers me. Don't they have any manners on how to approach a woman?