(a) The commissioner shall apportion the cost of the annual fees for the licensing of motor buses to motor common carriers of passengers for hire operating a fleet of two or more motor buses either interstate, or both interstate and intrastate, under the authority of the Interstate Commerce Commission or under authority of both the Interstate Commerce Commission and the Public Service Commission of this state. The apportionment shall be done so that the total cost of the fees shall bear the same proportion to the annual fees for motor buses as the total number of miles traveled by the fleet of the carrier in this state in both interstate and intrastate operations during the preceding year bears to the total number of miles traveled by the fleet during the year in both interstate and intrastate operations.

(b) The commissioner shall promulgate rules for the apportionment required by this Code section. The rules shall provide that the apportionment apply as nearly as practicable to each class of vehicle operated by the motor common carrier of passengers for hire.