Decided to go to goodcarbadcar.net to get US sales numbers (they have Canada as well) to see how much of this volume it represents.
In 2015 the Ford Brand sold ~2.502M vehicles in the US. For the cars being moved over to Mexico...
* C-MAX - 21,768
* Fiesta - 64,458
* Focus - 202,478
* Total - 288,704
About 11.5% of units sold in the US, and I think all the vehicles they sell in the US on their B3 (Fiesta) platform. Interestingly, not all C1 platform cars are moving over, as the Edge (124,000 units) and Transit Connect (52,000 units) will continue to be built in the US, again, because they offer better front-end margin.