Growth Rates in Power Pivot

Hello everyone,

I seem to be in need of your expertise on an issue. I basically have a table which contains data for different products on different weeks + weekdays. I also created a slicer which the user can use in order to switch between quantities and revenue.

What I am trying to do, is to add a measure which calculates the weekly growth rate (so [current week / previous week] -1, shown in %). I would like to note that it is important to do the weekly comparison on the same period - so for example if I want to see the growth rate next week on a Wednesday, it should basically be this week's Mon-Wed vs. last week's Mon-Wed.

The other option would be to show this difference as a calculation on the Grand Total field, but the issue is, if I select and proceed with any calculation it won't just show up as my grand total, but on every other value for every week and weekday.

Is there a possibility to show the calculation just on the Grand Total column or add an additional KPI column to my table with a growth rate formula ?

I am very grateful for your help and I am looking forward to your replies!

Thank you!