the few, the proud

I've been giving blood recently and the little motivational booklet they mail says that only 5% of Americans give blood. It also says that 30% of first-time donors give a second time...so, if we round off the population at 300k, then I get 4,500 Americans have given blood to the red cross more than once.
I also learned that I can give my blood to over 80% of Americans but only receive from less than half. I suppose that counts as altruism. I don't think we need to be told that god is love to help out our brothers and sisters.