In reality it does not matter if you know your blood type. This is because no Dr would rely a patient's assertion that their blood type is x. Get it wrong could mean death.
The only people who would get away with a wrong blood type are the Oneg.
Had a patient who gave birth. She was Rh-. She said her partner was also Rh-. (if mother is Rh- then anti D injection is given so I think she was thinking she did not need it). But the baby was Rh+:shock:
Apparently partner was indeed Rh- but obviously not the father......
.....
In Australia
In descending order of "rareness" IIRC:
O,A,B,AB
Rh- is rarer than Rh+
I think O+ is about 45% of pop
AB- is the rarest - <1% of pop
Geographical differences exist. For example Asian countries O- is extremely rare 1% or less. whereas in OZ its about 10%.