(

a) In addition to the increase in allowance authorized by and granted pursuant to the provisions of

Section 21313, and notwithstanding the limitation on those increases imposed by this article, the monthly allowance paid with respect to a local member, other than a school member, who retired or died prior to July 1, 1974, shall be increased by the percentage set forth opposite the period in the following table during which retirement became effective or death occurred: Period during which retirement or death occurred: Percentage: On or before December 31, 1965 7% 12 months ending December 31, 1966 6% 12 months ending December 31, 1967 5% 12 months ending December 31, 1968 4% 12 months ending December 31, 1969 3% 18 months ending June 30, 1971 2% 36 months ending June 30, 1974 1% (

b) The percentage shall be applied to the allowance payable on the date this

section becomes applicable to the contracting agency, and the allowance as so increased shall be paid for time on and after that date and until the first day of April immediately following the date of application. The base allowance shall be the allowance as increased under this section. The base year for annual adjustments of allowances increased by this

section shall be the calendar year preceding the year of increase if the increase date is after April 1st of any calendar year, and the second calendar year preceding the year of increase if the increase date is on or before April 1st of any calendar year. (

c) This

section shall not apply to any contracting agency unless the agency elected to be subject to the provisions of this

section in its contract with the board on or before December 31, 2001.