Running Total Average in a Pivot Table

[MCTampa]

Good afternoon,

My data has two elements: Revenue Transaction Volume (RTV) and Net Revenue Amount (NRA). I am trying to solve for Average Weekly Rate (AWR).

In a standard pivot table, AWR is an easy calculated field: AWR = NRA / RTV
For example:
[TABLE="width: 500"]
<tbody>[TR]
[TD]Date[/TD]
[TD]RTV[/TD]
[TD]NRA[/TD]
[TD]AWR[/TD]
[/TR]
[TR]
[TD]7/30/2017[/TD]
[TD]20[/TD]
[TD]$500[/TD]
[TD]$25.00[/TD]
[/TR]
[TR]
[TD]7/31/2017[/TD]
[TD]15[/TD]
[TD]$450[/TD]
[TD]$30.00[/TD]
[/TR]
[TR]
[TD]8/1/2017[/TD]
[TD]25[/TD]
[TD]$500[/TD]
[TD]$20.00[/TD]
[/TR]
</tbody>[/TABLE]


However I am trying to achieve the same result using the running total feature in a pivot table:


[TABLE="width: 500"]
<tbody>[TR]
[TD]Date[/TD]
[TD]RTV[/TD]
[TD]NRA[/TD]
[TD]AWR[/TD]
[/TR]
[TR]
[TD]7/30/2017[/TD]
[TD]20[/TD]
[TD]$500[/TD]
[TD]$25.00[/TD]
[/TR]
[TR]
[TD]7/31/2017[/TD]
[TD]35[/TD]
[TD]$950[/TD]
[TD]$27.14[/TD]
[/TR]
[TR]
[TD]8/1/2017[/TD]
[TD]60[/TD]
[TD]$1,450[/TD]
[TD]$24.16[/TD]
[/TR]
</tbody>[/TABLE]

My problem is that I cannot get the AWR to perform it's function when I am using running totals. It appears to simply be calculating the appropriate AWR for that transaction date or line of data.

Is there a way to do this within a pivot table using running totals?

Thanks,
Mike