The rest are of blood group A. Other Indian tribes have a great many people of blood group A, some as many as 80 percent of the people. Inhabitants of Asia are more commonly of blood type B than are people who live elsewhere. O is the most common. Blood type A is next, and blood type B is after that. Blood type AB is the least common.
Scientists try to go further than just the blood types.
They try to determine how many of each type of gene are present. For instance, we know that every person of blood group O has two O genes and every person of blood group AB has one A gene and one B gene. However, a person of blood type A may have an O gene or may not. Once you've calculated the number of hidden O genes, you can tell exactly what percentage of each gene is present in a particular population. In this way one determines the gene frequencies in a gene series.