68.The supplementary benefits plan shall, in respect of a person to whom the second paragraph of section 31 applies, provide for an adjustment to the reduction provided for in the said paragraph in order that the reduction does not exceed
(1) 1/12 of 1% computed for each month in which an early retirement pension is paid between the date of the person’s fifty-fifth birthday and the date of his sixtieth birthday;
(2) 1/6 of 1% computed for each month in which an early retirement pension is paid between the date of the person’s fiftieth birthday and the date of his fifty-fifth birthday;
(3) 1/4 of 1% computed for each month in which an early retirement pension is paid prior to the person’s fiftieth birthday.