Average of count in pivot tables
 

I have a table with 3 columns of text where column A maps to multiple values
in col B which maps to multiple values in col C.

e.g.
A B C
A B D
A E F
G H I

I'm trying to make a pivot table that shows me:
Col A Col B Count of Col C per Col B

Summarized by the total count of Col C as well as the Average Count of C per
B. So if there were 1 C for each B, the average would be 1. If each B had 2
Cs, the average would be 2, etc. I can't seem to find a way to show that
subtotal and overall total (so across all of A, the total number of C divided
by the total number of B). I can only average the value, which in this case
returns an error since it's text.