It's hard to pin down exactly how much of the depreciation of the U.S. market is attributable to the dollar. I do want to say, though, that the U.S. market started to depreciate in visitations after 2002, and the appreciation of the Canadian dollar didn't start until about three years ago. So the U.S. market started its downward trend well before, about two years before, the appreciation of the Canadian dollar.
On December 4th, 2007. See this statement in context.