Is a simple friendship too much to ask for?

Ok, so to start, I am 16 and a soon-to-be junior in high school. :D But that's not why I'm annoyed. I was extremely awkward in middle school, but freshman year in high school I had come out of my "ugly duckling" stage, and for some reason I noticed that I began forming more friendships with guys. Now I am not really in to the whole"high school dating" scene, and I prefer to just be friends with guys. That doesn't work out so well. Every time I make a new guy friend, it's great at first. We joke around and have non ual fun with each other and I really show my true colors. Keep in mind I do nothing WHATSOEVER to lead anyone on. After a little while, the guy asks me out, I say no, and they keep pestering me about it. I eventually have to end the friendship with the guy because I just feel so awkward, idk. I don't even know what the big deal about me is, I mean, I'm nothing to brag about. I easily blend in with the hundreds of other girls in my school, why can't they go after one of them? I just want a PLATONIC friendship with a male, because I tend to get along with them better than females. Is that too much to ask? How do I make them stop liking me more than a friend?