The Positive Test Result

A disease affects 1 in every 1000 people. A test for it is quite good:

• If you have the disease, it comes back positive 99% of the time.
• If you don't have it, it still comes back positive 2% of the time (a false positive).

You take the test. It comes back positive.

What is the probability that you actually have the disease? Answer as a percentage, rounded to one decimal place.