How to show increase change month over month

[theboss-123]

Hello ,

This is my second post regarding how to show increase varation of sale amount (CA) month over month of each year

any quick reply will be greatly appreciated

[theboss-123]

I added this expression and it is worked 

=(Sum(Montant)/Above(Sum({<month>}Montant)) - 1) * Avg(1)

and now it still to how display change in combo chart

like this example