I would say 60% coal, 20% wood, and 20% propane. I usually have a 500gal propane buy-in to guarantee the annual price. Plus, in the spring and fall my bride won't let me use wood or coal on cool but not cold days, because the wood/coal furnace cranks out so much heat. So, for those "shoulder" times, we use propane, as well as for dryer, hot water, and stove. By the end of October, however, when it starts getting really cold, coal and wood are the order of the day. I burn wood for about 8 hours after burning coal for a couple of days, so that I can get rid of the coal ash more easily during shakedowns, and to use up any unburned coal pieces.