Pivot Calculated Field doesnt help

I have a pivot table with my capex and opex hours in the columns with the names of project managers in the rows. the Capex and Opex hours are also summed into a column for a monthly total(see pic).

What I need is an extra column at the end of each month that shows the capitalization rate which is just CAPEX/MONTHLY TOTAL in % however I can not figure out at all how to do this. none of the %Of options work to do this what is wrong?

Any help is appreciated

EDIT: I understand a sample worksheet would help but it would take an immense amount of time to create one with non sensitive info that would help so the pic is all I can provide.