M_Boats: Foresail Size??

If I'm to order new main and jib for my Monty 15 (which I'm likely to do soon): What size range (100%, 110%, 120%, etc) jib makes the most sense. I believe the boat came standard with a 100%. I can only afford one jib at present. My sailing will be primarily near shore Great Lakes (Lake Huron, Tawas Bay, North Channel, Georgian Bay) and smaller inland lakes. I'm guessing my winds typically to be 5-18 MPH. My main will have two reefs. Thanks for any and all advice. *Jeff+* Molōn labe!