Any employee who qualifies for membership in the retirement system under §§ 8-3410, 8-3412, and 8-3413 may elect, on or after July 1, 1947, to become a member of the system, at which time payroll deductions shall begin, such contributions to be credited to such member’s account. Anything in §§ 8-3429 – 8-3437, to the contrary notwithstanding, on or after July 1, 1961, the rate of contribution of any member who is a commissioned member of the department of safety shall be eleven and seventy-three hundredths per cent (11.73%) of such member’s compensation.