For any fiscal year commencing on and after July 1, 1975, in determining the allocation of any operator pursuant to Section 99285, the public transit service mileage of any operator which has lost any days of operation due to strikes occurring prior to August 1, 1975, civil disorders, or acts of God shall equal its actual public transit service mileage times the number of days it would have been in operation but for such causes, divided by the number of days it was in actual operation.