Calculations using totals generated in Pivot Tables
 

I have created a series of pivot tables showing sales totals by months by
various sales staff in various states.
As the mumber of staff in each state varies the number of lines in each
table varies when the state is changed.
I would like to calculate the average sales total for each state and the
average sales by sales person year to date, and then calculate how far each
sales person is above or below the average.
Is there a way to calculate using the totals generated by each table, from
within the table?