Statistical distribution of the major blood types in the U.S.:
O+ 37.4%
O- 6.6%
A+ 35.7%
A- 6.3%
B+ 8.5%
B- 1.5%
AB+ 3.4%
AB- 0.6%
The rarest blood type found is called bombay blood (subtype h-h), found only in a Czechoslovakian nurse in 1961 and in a brother and sister in Massachusetts in 1968.