Average of a Summary

[DarrylO]

I'm trying to create a report that will display a group of monthly transactions, a subtotal by month (summary field), and an average of the monthly subtotals. I can easily get the monthly subtotals by creating a summary, but as most of you know, you cannot create a summary field based on another summary field. Using the Average function on the monthly subtotal field doesn't work; and I've tried the GetSummary function with no luck.

I know I can create a new table and set up a calculation to display the monthly average there, but I'd like to show the transactions, subtotals and average in the same table. Any ideas?

[comment]

Do you know how to count the number of months included in the report?