US auto/trucks sales per year averages around 17 million. Mexico, 1 million. 1/17 of US sales.
I was looking at auto sales data here -
http://www.tradingeconomics.com/united-states/car-registrations
...but didn’t correct for monthly vs. yearly numbers...:^(
Still comes out as 7:1 though.
Perhaps because it’s passenger car numbers only, and not trucks?