Blood banks are concerned with collecting and distributing blood to hospitals to help people who are very sick or injured. People can only accept a blood transfusion of a select few other blood types, if any at all, so it is important that blood banks maintain stock of all types of blood. The population of blood types in the United States are as follows: O- O+ A- A+ B- B+ AB- AB+
7% 38% 6% 34% 2% 9% 1% 3%

A person can only have one blood type, so we can say that the probability of having more than one type is mutually exclusive. What is the probability that a random blood bank donor will have O- or O+ blood?