N.D. Cent. Code § 15-39.1-10.7
An individual who on June 30, 1991, is receiving monthly benefits from the fund on an account paid under this chapter or under former chapter 15-39 is entitled to receive three dollars per month multiplied by the individual's number of years of credited service for individuals who retired before 1980, two dollars per month multiplied by the individual's number of years of credited service for individuals who retired after 1979 and before 1984, or one dollar per month multiplied by the individual's number of years of credited service for individuals who retired after 1983 and who retire before July 1, 1991, or an increase of ten percent in the individual's currently payable annuity, whichever is greater. The minimum monthly increase under this section is five dollars and the maximum monthly increase under this section is seventy-five dollars.
N.D.C.C. § 15-39.1-10.7