This is a question that depends on the divergence in the inflation paths in the two countries. In the example that I gave there was a swing of some 75 basis points between Canada and the United States during 2015. There have been other episodes similar to that.
The truthful answer is that it only depends. I couldn't speculate on what is the maximum divergence we could sustain, but it would just depend on the underlying shocks.
I remember studying the early 1970s when Canada first went back to a flexible exchange rate. There was a massive divergence between the Canadian and U.S. economies at that time, and the exchange rate, as soon as it was unleashed, rose by some 10¢ in a very short space of time because of that divergence.
Really, I think the most important thing that helps us equate when there is a divergence is the exchange rate. Interest rates are less the engine of correcting that. They're more of a facilitator, if I can put it this way.