On the Sorting/Grouping tab, select Grand Totals to display the sum of the elements from all the groups.
Grand totals also display the sum of any columns with subtotals.
Select a display option from the drop-down menu:
Title, count, and totals. Title shows the header information. Count shows the number of elements in the group. Both title and count appear left-justified below the group. Total shows the subtotal below a column that can have a total. Examples of columns having subtotals are Cost and Count. You add these columns using the Formatting tab.
Title and totals. Displays title and subtotal information.
Count and totals. Displays count values and subtotals.
Totals only. Displays subtotals only for those columns that can have them.