Blood group O is often considered the most common blood type globally, with varying prevalence in different regions. It's estimated that around 40% to 50% of the world's population has blood group O.
Blood group A is the second most common blood type, with an estimated prevalence of around 30% to 40% worldwide.
Blood group B is less common than A and O but still prevalent in many populations. It's estimated that around 10% to 20% of the global population has blood group B.
Blood group AB is the least common blood type globally, with an estimated prevalence of around 5% to 10%.