Below is an example, wondering what you missed was the 1/30 and 1/20 manufacturer usage in each region.
For Americas, it is:
12000*0.3*0.6*50000/30 = 3.6m
Most commonly omited factor is the below one, that case you may got 108m instead (using Americas as an example)
Feel free to reach out if any follow up Qs, cheers!
Han
Company case by