The people of the city, by their approval of ordinances 97 and 170 at the elections hereinabove provided, hereby authorize the city council by ordinances duly enacted to make such administrative and technical changes or additions in the method and manner of administration and enforcing this chapter as may be necessary or proper for efficiency and fairness except that the rate of the tax herein provided shall not be changed without approval of the qualified elector of the city as provided by law. (1985 Code ch. 7 § 1-22)