(1) After December 31, 1980, a retirant or beneficiary of a deceased retirant whose effective date of retirement benefit payable was before July 1, 1956, shall receive a supplemental to his or her retirement allowance in an amount sufficient to produce a total retirement allowance including all other supplements and adjustments of not less than $160.00 multiplied by the retirant's total number of years of retirement service credit.

    (2) A supplemental retirement allowance provided by this section shall be paid only during those fiscal years for which an appropriation is made which is sufficient to cover the additional payments likely to be made.