After the date a system becomes operative the board of supervisors shall, in the preparation and adoption of the county budget, add to the appropriation for salaries and wages and include therein an appropriation determined pursuant to Sections 31453, 31453.5 and 31454. Until such determination the additional appropriations shall equal 23.77 percent of the total compensation provided for all safety members covered by Article 7.5 (commencing with Section 31662) and 8.85 percent of the total compensation provided for all other employees who are members of the retirement association.