The subtotal function is a function which returns a subtotal in a database or a list. Subtotal can help you to analyze your data in a much easier format.
Step 3: In the Subtotal mask choose for “At each change in: Year”, “Use function: sum”, “Add subtotal to: Sales ($)”, “Replace current subtotals” and “Summary below data”. After that click on the “OK Button”.
Step 4: Now you see the effect of the subtotal function. Under each year the data is aggregated into the yearly total (2013 Total, 2014 Total and 2015 Total) and all sales are aggregated into the grand total.
Step 5: You can now click on the little numbers in the top of the left corner (1, 2, 3). If you do this, the data will be aggregated in a less detailed table. This can be useful if you do not need detailed information.