County courts are hereby authorized to lay not in excess of the following maximum levies, for the purposes specified and in the following order:
(1) With respect to the county as a whole for the payment of (a) interest and sinking fund requirements for bonded indebtedness incurred prior to the adoption of the Tax Limitation Amendment; and (to the extent not so required), (b) other legally incurred contractual indebtedness, not bonded, if any, incurred prior to the adoption of the Tax Limitation Amendment, of the county as follows: On Class I property, twenty-five one hundredths of 1¢; on Class II property, one half of 1¢; and on Classes III and IV property, 1¢.