A custom column in pivot Table

[Pragun]

I want to add a calculated column in the pivot table(% of progressive status) which would take an expression and calculate it on the basis of data in that row.

currently I have :

row : Insp.Lot Origin

Column : MonthYear

How can this 3rd column be added to the pivot table

[jonathandienst]

Please explain the calculation you would like to perform.

[Pragun]

in the pivot table I am showing lets say pending lots. In the calculated column I want to show sum of all pending lots from all the months divided by total lots for all the months for the given Insp.Lot origin