Pivot Table: Calculated Field based on Running Total Field

So I've been searching for a while this morning with no luck so far - I'm not even sure it is possible to do what I am trying to do....

I have a Pivot table similar to the following:
Snap2.png

Widget, X, Y & X/Y come from the data

X(RunTotal) & Y(RunTotal) are simply X & Y, shown as Running Totals

X/Y (RunTotal) (orange column) needs to be "X(RunTotal) divided by Y(RunTotal)" at each row (as I have in the image)....but it's coming back as the same as X/Y since X(RunTotal) and Y(RunTotal) are just running total fields of X & Y.

I'm wanting this in a pivot table because I'm using a pivot chart with slicers to let users dynamically filter the data. Outside of a pivot it's easy...inside of one, I'm coming up short.

Any help??? Is this even possible?

Thanks!