B negative
1.3% of the Dutch population has blood group B-negative (B-). People with blood group B-positive, B-negative, AB-positive and AB-negative can receive blood from someone with blood group B-negative. Therefore this blood group is very rare, but there are many people who can receive this blood group from donors.
Women are allowed to give blood a maximum of 3 times a year, men up to 5 times a year. How often you are called upon depends on the blood group that is needed at a certain time.