Pivot Table Show as Difference from last row same column

Hello good people trying to help 🙂,

I have this Pivot Table (created from a Data Model):

Orientation:

The Pivot Table's Report Layout is Tabular Form:

"Park" and "Audit Date" fields are in the Rows section

"Average Performance" is in the Values section (Summarized by Average, Show as No Calculation, Formatted as percentages).

Note that Park A had 3 audits, other parks had 2 audits each.

The Task:

For every audit, as long as it is not the first audit for that park, I want to display the difference between the current audit's Average Performance and the previous audit's Average Performance.

If it is the first audit for that park, nothing will be displayed (because there is no audit to compare with).

So, for park A, in the first audit nothing will be displayed (because there is nothing to compare with). In the second audit it will show -15.73% (because 78.82-94.55=-15.73). In the third audit it will show 17.07 (because 95.89-78.82=17.07).

Is that possible? I tried "Show As" + "Difference From" for the Average Performance column, but the (same) Average Performance column is not available as an option for the "Base Field", only the other columns in the table are available to choose from.

Thanks for reading until here. Will appreciate any help.