If you're bisexual, do you prefer men or women?

I think I would have to consider myself bisexual as I have had sex with both men and women. I'm a man myself but I don't think true bisexuality actually exists. Even though I like both, I definately prefer women. I could never get romantic with another guy. I think bisexual people usually have true preference for one or the other, even if they like both. I'd say I'm 70% for women and 30% for men.