Contributions in the form of a deduction from compensation under section 473 of this title shall cease for any group A member who attains 25 years of creditable service and the member shall continue to accrue creditable service, without such a contribution, at the rate of 1 2/3 percent until the member retires. Any group A member in service on January 1, 1991 who, as of that date, has made contributions for more than 25 years but less than 30 years shall, upon normal retirement, be granted up to five years of additional creditable service at the rate of 1 2/3 percent for each year or part of a year in which contributions were made in excess of 25 years. Any group A member in service on January 1, 1991 who, as of that date, has made contributions for more than 30 years shall, upon normal retirement, receive credit for contributions in excess of 25 years and in addition shall be granted, upon normal retirement, five years of additional creditable service at the rate of 1 2/3 percent. (Added 1989, No. 277 (Adj. Sess.), § 17t, eff. Jan. 1, 1991.)