Try running the "Invoice Item Detail Wirth Pricebook" report. Set Date Type, From-To field dropdowns. Make sure you have the "Item Type" column shown and set it to filter it to only service. You can then drag the item name column header into the grouped by purple section. It should group each service task now and at the bottom of the first group click one of the drop downs and select count. It should show the number of line items in that group. Now when you click export, select pdf or excel file and then check the "Export only aggregated data" box.
