In order to calculate the total number of breakfasts of a season, you need to run two reports:
Product report for all "stay product" breakfasts
Accounting report for all "billing screen" breakfasts with these settings:

Hint: The Excel export (accounting report) won't show the "Count", just the revenue. Therefore the Excel export is not helpful in that case.
Keep in mind: If breakfasts were added / refunded in a not correct way (for instance just € 120,- with 10xbreakfast in the note), it won't be counted correctly.
Keywords:
Breakfast, report, reporting