Beginning with the 1973-1974 school year and in subsequent years, unless the formula relating to reimbursement is revised by either the State Board of Education or by the General Assembly, the maximum allowable costs for contracted transportation or transportation by district-owned vehicles shall be subject to an annual percentage increase or decrease. This annual adjustment shall be determined in accordance with the percentage of increase or decrease in the consumer price index established by the United States Department of Labor for the calendar year immediately preceding the year of operation.
22 Pa. Code § 23.39