In an Excel [2003] pivot table, I need to calculate a new field based on the
COUNT of one field and the SUM of another (and other similar calculations).
Take the following example:

Date
1/1 1/2 1/3 Total
CountOfCustomers 10 20 15 45
SumOfBigCustomers 5 10 10 25
% Big Customers 50% 50% 66.7% 55.6%

How would I create the "% Big Customers" field? I know in this example it
would be easy since I am dividing by the total # of customers and I could
just take the AvgofSumOfBigCustomers (5 divided by the number of records in
the set 10 would produce an average of .5 or 50%). But what if it were two
fields that wouldn't permit me to use the built-in summaries? In other words,
how do I use two different SUMMARIZED fields in a formula to calculate a new
field (i.e. =SumOfBigCustomers / CountOfCustomers)?

Let me know if this doesn't make sense and I will try to provide a better
example.

Thanks.