Running Sum (RSUM) of Unique Count of Customers in a filtered line chart

I'm trying to do a running sum of a unique count of customers in a Tessitura Analytics Line Chart.

Anyone have an example of this working.

More specifically, I'm trying to do:

A running sum of unique customers by geo area for the season.

I Then I want to compare this years growth with the growth for prior years sales.

If this will help me, I do have the luxury of having access to the RMA Tessitura Analytics Cube.

Thoughts?

Thanks.

--Tom