Special column in pivot table - defect per unit calc

Hi there.

I try to solve very hard issue (maybe hard only for me)

I try to dynamically calculate (in pivot table) parameter which i called defect per unit.

Lets imagine we have column A with various type of defects, column B with vehicle number..

If i would like to calculate defect per unit, it should be : count of all defect1 / all checked cars... in my case divide by 3 every time. And here is the issue.

Anyhow i add pivot to data model - anyhow i create special distinguis calc of vehicles (means unique), anyhow i add new measure in new column, i can only divide count of defect with related cars... But not all cars count as i need :-/

Please could you help me ?

Here are pictures and excel attached :

Screenshot_2023-03-28 15.36.45_thz9qu.png

Screenshot_2023-03-28 15.37.38_mpOWi2.png