A system of insurance premium discounts and surcharges based on the accident history applied to non-fleet contracts. The term non-fleet contracts refers to contracts where the total number of contract automobiles owned and used by the policyholder (the number of contracts with other insurance companies included) is nine or less. (Cases where the number of automobiles is 10 or more are referred to as “fleet contracts.”) The grades are divided into 20 levels (Grade 1 to Grade 20), and the grade is maintained even if the insurance company changes.