As we all know human blood is grouped into four types: A, B, AB, and O with each letter refers to a kind of antigen, or protein, on the surface of red blood cells. The percentages of people having these blood groups in the United States is:
O - 45%
A - 40%
B - 11%
AB - 4%
A - 40%
B - 11%
AB - 4%