Trudy has been training for a marathon. She has kept track of how many miles she runs everyday for the past two weeks: 12, 15, 7, 14, 12, 3, 16, 15, 19, 20, 12, 9, 18, and 21. Trudy's coach says that he should be able to choose any day at random from the last two weeks, and Trudy should have run more than 13 miles if she is to be ready for the marathon. What is the probability her coach chooses a day from this list from the last two weeks with more than 13 miles listed? Write your answer as a fraction please.