The State Board of Education shall establish a salary schedule for school principals that includes a supplement amount for each principal. The amount of the supplement shall be based on the amount appropriated by the General Assembly for this purpose each year divided by the total weighted full-time equivalent count for the state. The amount for each principal shall be determined by multiplying the amount per weighted full-time equivalent count by the weighted full-time equivalent count for each school. Local school systems shall pay this supplement to each local school principal.