Actual VISAs, as opposed to entry status, are hardly ever issued to Canadians for any reason, let alone TN, quite simply because Cdns are visa-exempt for most statuses. For example, you have NEVER had a visa issued in all your years on TN (surprise!). Visas are sometimes issued at far-flung consulates, to avoid a potential candidate from flying all the way to US just to find they are ineligible.
Given the numbers you quote for Mexicans, and the fact that TN can last indefinitely and is more easlily qualified that H1, you can assume that there are just as many TNs as L1 and H1 workers out there, if not more.