I have a pivot table that breaks out data from multiple departments and categories by both month and year. I want to have a subtotal section at the bottom that sums the data based on the the Row Label categories. Any thoughts?

Jan Feb Mar
Row Labels 2010 2009 2010 2009 2010 2009
Dep1 6 7 14 8 18 15 20
Cat A 3 2 7 2 8 6 8
Cat B 0 0 1 0 1 0 1
Cat C 3 5 6 6 8 9 10
Cat D 0 0 0 0 1 0 1
______________________________________________________________________
Dep2 7 7 10 12 13 18 19
Cat A 5 4 6 7 7 11 10
Cat B 0 1 0 2 0 3 0
Cat C 2 2 3 2 5 3 8
Cat D 0 0 1 1 1 1 1
______________________________________________________________________
Dep3 0 0 3 1 7 3 9
Cat A 0 0 2 1 4 2 6
Cat B 0 0 0 0 0 0 0
Cat C 0 0 1 0 3 1 3
Cat D 0 0 0 0 0 0 0
______________________________________________________________________
Subtotal
Cat A ? ? ? ? ? ? ?
Cat B ? ? ? ? ? ? ?
Cat C ? ? ? ? ? ? ?
Cat D ? ? ? ? ? ? ?