I do not know the extent of Canada's commitments to the OECD with regard to providing specific data about its population. However, I do see how this would be useful. It is not just a question of legality or obligation. It is also Canada's credibility as a modern society that is at stake. It deals with other societies that make the effort to study the reality of their own populations. It is a question of international credibility.
On August 27th, 2010. See this statement in context.