If you bill sewer based on the average water usage for a specified period of time, that sewer average is stored in each customer's record. The sewer average is not calculated by this program, but this program is designed to allow you to print a listing of the average sewer usage that is currently in each customer's record. The program can be run at any time.
The Less Than will be the largest usage that will be shown. If you want everybody to print, it should be a number larger than any customer's actual average. The Greater Than would normally be 0 to allow all customers to print.