On his blog, JP Koning reports that

[b]oth the Christmas bump and the sawtooth pattern arising from monthly payrolls are less noticeable than previous years. But these patterns remain more apparent for Canadian dollars than U.S. dollars. Not because Canadians like cash more than Americans. We don’t, and are probably further along the path towards digital payments then they are. Rather, the percentage of U.S. dollars held overseas is much larger than Canadian dollars, so domestic usage of U.S. cash for transactions purposes gets blurred by all its other uses.