Difference between bisexual and pansexual... I think people could probably argue about this a lot. My sense is that 'pansexual' people are a lot less about gender labels, and that someone's gender is irrelevant.
Me, I wouldn't say I am pansexual. Because, although I do like both men and women sexually and romantically, I don't think I would want to date anyone who is transgendered (although I can respect them and have no problem with them). Also, gender does matter to me... in terms of, there are times I want to be with a man. And there are times I want to be with a woman. So it's not like every person is just a human and gender has no relevance to me. If that makes sense.
And, if 7 out of 24 are bi, that is a very high percentage, yes. I remember hearing that 10% of the US population is supposed to be gay/lesbian. But, I am not sure if that is supposed to include bisexuals as well.