Don't Summarize Matrix Subtotal?

I have a complex table of logic that needs to contain various subtotals in the Matrix view.  Within the Matrix view I have a list of monthly values that I calculate a monthly percentage.  The Matrix subtotal of the percentage is taking the previous two columns as a calculation instead of the average of the percentage.

I.e. in my screenshot the percentage is showing 56.58/5.91=970.99%.  Instead I would like to see the average of the percentages as an average.

Is there a way to average a single column in a Matrix?  If it matters the % column is a measure not a calculation in the query.  I was hoping to avoid writing a new query to calculate the percentage but I do know how to do that if that is the only resolution.

Thanks in advance!