(1) Effective January 1, 1988, but before any of the increases provided by section 23c on or before January 1, 1988 are included, the monthly retirement allowance payable to a retirant or retirement allowance beneficiary and determined upon the date of retirement of the retirant whose retirement allowance effective date was before January 1, 1979 is supplemented as follows:

Effective Date of Retirement	Percent of Increase
October 1, 1977 to December 31, 1978	10
October 1, 1976 to September 30, 1977	11
October 1, 1975 to September 30, 1976	12
October 1, 1974 to September 30, 1975	13
October 1, 1973 to September 30, 1974	14
October 1, 1972 to September 30, 1973	15
October 1, 1971 to September 30, 1972	16
October 1, 1970 to September 30, 1971	17
October 1, 1969 to September 30, 1970	18
October 1, 1968 to September 30, 1969	19
October 1, 1967 to September 30, 1968	20
October 1, 1966 to September 30, 1967	21
October 1, 1965 to September 30, 1966	22
October 1, 1964 to September 30, 1965	23
October 1, 1963 to September 30, 1964	24
October 1, 1962 to September 30, 1963	25
October 1, 1961 to September 30, 1962	26
October 1, 1960 to September 30, 1961	27
October 1, 1959 to September 30, 1960	28
October 1, 1958 to September 30, 1959	29
October 1, 1957 to September 30, 1958	30

(2) The recalculated retirement allowance as supplemented by this section shall be the basis on which future adjustments to the allowance are calculated.