People who donate substantial amounts of their income to charity are rare. Why is such an unusual thing to do? I think a lot is that is just seems weird, no? Who do you know that does that?
Well, there's part of the problem: our cultural norm is to be quiet about giving and money. It makes sense: you can have all sorts of conflicts about money, and it would be unseemly for helping people to be turned into a game of one-upmanship. But on balance I think that norm is harmful: if more people were public about their giving it would appear less unusual. And if you do end up with people competing for status via giving, well at least their competition has highly beneficial side effects, as opposed to just yielding bigger cars and houses.
So I encourage you to make your giving public, in the hope that it will inspire others. You don't have to broadcast it; putting it up somewhere other people can find it if they're looking is good too, but get it out there where people trying to get a sense of how much giving is socially normal can see it. As a step in this direction I've made a page listing my donations.
(Inspired partly by Yvain's similar post.)