Almost nothing. Cooking is only about 6% of a home's energy consumption. You'd have to calculate the number of hours of usage by your average elecric rate vs the BTUs used by the range in question. Propane has traditionally been higher than most electric rates,but that is location specific. And it's such a minor consideration as to be nonexistant.

What IS important is if you are in a heating or cooling climate predominantly. If you are in a cold climate, the 60% of heat that goes ito the room with gas cooking might be welcomed, whereas it will only add to the AC load in a cooling climate. In a cooling climate, induction makes much more sense from an energy efficiency standpoint. It makes sense from a cooking standpoint too. You should check it out.

GreenDesigns is right.

If you want numbers for your particular (or peculiar) situation, try the calculator at this link.

http://michaelbluejay.com/electricity/cooking.html