Commencing on July 1, 1990, every retirement allowance payable by the San Francisco City and County Employees' Retirement System, to or on account of any person who was retired prior to July 2, 1988 as a member of said system under sections 8.507, 8.509, 8.584, 8.586 or 8.588 of this Charter, is hereby increased by the amount of $50.00 per month, provided such member had retired prior to July 2, 1964. If the member had retired after July 1, 1964, then said monthly increase shall be an amount which shall bear the same ratio to $50.00 that the number of years the member has been retired bears to twenty-five (25) years.
In computing years of retirement, the Retirement System shall count completed fiscal years between the member's effective date of retirement and June 30, 1989.
This section does not give any member retired prior to July 1, 1990 or his successors in interest, any claim against the City and County for any increase in any retirement allowance paid or payable for time prior to July 1, 1990.