Relative contribution to percentage change

[fallingfirst]

Would greatly appreciate any help on this finance maths problems I have been trying to solve for days.

The total change in PGM% from 2022 to 2021 is 3%. How can I calculate the relative contribution of each product to this 3% change?
I.e. if I were to add up the PGM% variance of all products, it should sum up to the total % variance.
What formula should I put in column M to calculation relative contribution to percentage change?

 

[Joe4]

The total change in PGM% from 2022 to 2021 is 3%. How can I calculate the relative contribution of each product to this 3% change?

What exactly are "PGM" and "COS"? I am not familiar with those abbreviations.
And how do you arrive at 3% change from 2022 to 2021.
Please show us how you arrived at that number, so we can get a better understanding of how the calculations work.