We've actually done more than just propane. We've done a bit of both.
Part of that was initially in the piloting phase to try to understand which would operate best. As I mentioned in my presentation, we know there's no magic bullet theory today that's going to say this is the ultimate technology we must use on every route, in every vehicle, for the rest of time.
We've invested in a number of different technologies to evaluate and pilot. Propane is a larger technology right now in use in Canada Post than natural gas. The primary reason at this time for that is the cost of refuelling infrastructure.