How do I come out to my friends?

Hey so I'm an 18 year old English guy and I want to come out to my friends. I don't think they're actually homophobic but there's one gay guy among them and he gets made fun of sometimes and I don't want that. One time I told them I'm like 15% gay and they made fun of me just for that much idek what they'd do if I said I was like 100% gay. Please help.