I don't think as many Canadians are moving to the states as they used to. The tech sector in Canada is doing quite well, and many of the American companies that people used to move down south for have offices up here (EA Vancouver, for example). Even in Victoria, tech is the number one industry, and the talent pool is good enough to support serious players in industry, locally or foreign owned.
It's a self-selected survey, it's likely that people who have a higher desire to have their country of residence represented would be more likely to participate. I suspect that Canadians fall into that category.