I have a pivottable like this:

Col W Col Z Total
Row X 19 4 23
Row Y 12 6 18

I want to summarize the data by showing a percent of the current
running total. For example:

Col W Col Z
Row X (19/23) 82.6 (4/23)
17.4
Row Y (31/41) 75.6 (10/41) 24.4

I tried to to a calculated field (ColW/(ColW + ColZ)). Then set the
pivot chart to do a running total, but I got the following results:

Col W Col Z
Row X 82.6 17.4
Row Y 158.2 41.8

Is there a way to achieve what I want in Excel?