Can you please discuss the importance of having type o blood?

All are important: The ABO system is the most important blood-group system in human-blood transfusion. Any blood type is important and can save lives as a blood donor. Depending on the ethnicity and race blood types are in different percentage. Ie. For group o, native american indians 76%, us white 45%, us aa 49%, russian 33%, koreans 28%, irish 52%, arabs 34%, belgians 47%, japanese 30%, spanish 38%.