slicers for custom calculated field in excel pivot table/pivot chart

It can be done with Power Pivot but I don't think that is possible in your Excel Version
You need to use Power query to unpivot your original data in order to have AA1, AA2 as records in row. After that you need to create a measure as ratio between values and "n" column and create a Pivot Table from PowerPivot data model.
The query:

HTML Code: 

and the measure:

Formula:

ratio:=sum([value])/sum([n])