A certain disease is present in $2\%$ of a population. A screening test for the disease is positive $85\%$ of the time when the person has the disease and $7\%$ of the time when the person does not have the disease. Let $E$ be the event "the person has the disease" and $F$ be the event "the test is positive." What is the probability that a person actually has the disease given that they test positive?