*56.816.  Normal annuity, computation of — reserve account established, purpose. — 1.  The normal annuity of a retired member who served as prosecuting attorney of a county of the third or fourth class shall, except as provided in subsection 3 of this section, be equal to:

  (1)  Any member who has served twelve or more years as a prosecuting attorney and who meets the conditions of retirement at or after the member's normal retirement age shall be entitled to a normal annuity in a monthly amount equal to one hundred five dollars multiplied by the number of two-year periods and partial two-year periods served as a prosecuting attorney;

  (2)  Any member who has served twenty or more years as a prosecuting attorney and who meets the conditions of retirement at or after the member's normal retirement age shall be entitled to a normal annuity in a monthly amount equal to one hundred thirty dollars multiplied by the number of two-year periods and partial two-year periods as a prosecuting attorney.

  2.  The normal annuity of a retired member who served as prosecuting attorney of a first or second class county or as circuit attorney of a city not within a county shall be equal to fifty percent of the final average compensation.

  3.  The normal annuity of a retired member who served as a prosecuting attorney of a county which after August 28, 2001, elected to make the position of prosecuting attorney full time pursuant to section 56.363 shall be equal to fifty percent of the final average compensation.

  4.  The actuarial present value of a retired member's benefits shall be placed in a reserve account designated as a "Retired Lives Reserve".  The value of the retired lives reserve shall be increased by the actuarial present value of retiring members' benefits, and by the interest earning of the total fund on a pro rata basis and it shall be decreased by payments to retired members and their survivors.  Each year the actuary shall compare the actuarial present value of retired members' benefits with the retired lives reserve.  If the value of the retired lives reserve plus one year's interest at the assumed rate of interest exceeds the actuarial present value of retired lives, then distribution of this excess may be made equally to all retired members, or their eligible survivors.  The distribution may be in a single sum or in monthly payments at the discretion of the board on the advice of the actuary.