Beginning January 1, 1998, the salary of the city treasurer shall be, in addition to the amount provided by section 82.516, fifty-three thousand nine hundred dollars per annum and beginning January 1, 1999, the salary of the city treasurer shall be, in addition to the amount provided by section 82.516, fifty-nine thousand two hundred ninety dollars per annum. Beginning January 1, 2000, the compensation of the city treasurer may be annually increased by an amount equal to the annual salary adjustment for employees of the city of St. Louis as approved by the board of aldermen. The salary of the city treasurer, and the salaries of the treasurer’s deputies, clerks, and assistants, shall be paid out of the city treasury, in equal semimonthly installments.