most common blood ty
There are four main blood types: type A, type B, type AB and type O. Additionally, if a substance called Rh factor appears on the surface of the red blood cells, a person is considered to be Rh+ (positive). Type O+ is the most common blood type, while AB- is the least common. But not all ethnic groups have the same proportion of blood types. For example, Hispanics have a high number of O blood types, while Asians have a high number of B blood types.