A little help here.....?

there is a guy I know 4 years from school, and he keeps sending me mixed signals. Everything began 3 years ago when he sent me a note telling me he likes me. We are both teens. He is perhaps one of the hottest boys of the school .I am well..... normal, shy, and nice girl and I'm not that bad looking. Cause he is generally social with other girls at the beginning I thought that he was kidding , but he continued to do little things such as giving me " knowing looks ", pick up things for me, always initiate any conversation, asking me of homework or to borrow him a pencil, and "accidentaly" bump onto me. In the few times that teacher made us to sit together, I felt like some sort of electricity between us and i was unable even to speak. I dunno if he felt the same but he didn't speak to me either nevertheless.Other times he pretends that I don't exist, and sometimes he stares at me, and he even had asked me if I have a boyfriend, in a playful tone .( of course I didn't tell him ). Yet he respects me and he never teased me or anything like that .Yet he has never asked me out, .During these three years i'm still trying to figure out if he really likes me. And if he does, then why he doesn't ask me out ? I hear that he doesn't have any girlfriend, although he has many "admirers " ( my best girl friend included ) . So what d' you think??? does he like me ?