When creating a custom report you can select the summary information to include. This can be useful for numerical data, where you can retrieve totals and the minimum, maximum and average values, for example.
To select the grouping information to include in a custom report
Next step: Select Custom Report Column Order
Previous step: Select Custom Report Columns.
Additional Information
Select Custom Report Column Filters
Select Custom Report Output Options and Access Permissions
Select Optional Tables for Custom Reports (Advanced)
Select Custom Report Columns to Sort on (Advanced)