The amount of the pension for members of the police department of the city of Opelousas shall be increased by three and one-third percent for each year of service in the department over twenty years, but no such member shall receive a pension in excess of eighty-seven percent of the highest average monthly salary, for any continuous twelve-month period of time worked prior to retirement. The amount of the pension for members of the police department of the city of Morgan City shall be increased by two and one-half percent for each year of service in the department over twenty years, with such increases to cease upon the member attaining credit for thirty years of service.
La. Consolidated Public Retirement § 11:3547