I'd argue that 5-6% are bisexual and 3-4% are gay. Since most bisexuals are in opposite-sex marriages, there's no need for them to come out, so you don't notice them. A bisexual would only come out if he's in a same-sex relationship.

In fact, most gay people don't come out either. Not always out of fear, but mostly because we don't feel the need to tell our work colleagues that we're gay unless people asked us, and most people don't anyway. Being gay insist that interesting.