As a blood compatibility and transfusion specialist, I perform a lot of blood types on a lot of people just about every day I work.
Not counting Rh factors, type O blood is easily the most common at about 42% of the population. I have a hard time believing that 42% of this world’s population are confident leaders.
Also, individuals of African or Asian descent have a higher probability of being type B than Caucasians and Hispanics.