Annual or Monthly Basis: Service during 4 months in any 1 calendar year;
Weekly Basis: Service during any 17 weeks of any 1 calendar year, and service during any week shall constitute a week of service;
Daily Basis: Service during 100 days in any 1 calendar year, and service during any day shall constitute a day of service;
Hourly Basis: Service during 800 hours in any 1 calendar year, and service during any hour shall constitute an hour of service.
40 ILCS 5/9-220