How can I detect outliers within rows of a pivot table?

In the attached example workbook, I'd like to write a formula that detects expenditures that are outliers for each region in the 5-year period. I can do this outside of the pivot table by writing formulas with quartiles and IQR, but I would like to be able to do this within the pivot table so that it automatically refreshes. How could I do this?

Any help would be much appreciated!