Good day JohanSoderdahl,
First add a 3 new field (fieldA, fieldB, fieldC)then set a three rules on each dropdown list that:
if field1 is equal to a, set a field' value for FieldA value of FieldA+1.
if field1 is equal to a, set a field' value for FieldB value of FieldB+1.
if field1 is equal to a, set a field' value for FieldC value of FieldC+1.
Copy all the rules in all of your dropdown lists.