In order to assist school districts in financing needed capital improvements, the General Assembly shall annually allocate to the Board a sum equivalent to thirty dollars multiplied by the number of pupils enrolled in grades one through twelve of the public schools and, effective beginning in Fiscal Year 1988-89, fifteen dollars multiplied by the number of students enrolled in public kindergarten programs. The calculation must be based on the one hundred thirty-five day count of the average daily membership during the school year ending in the calendar year prior to the calendar year in which the fiscal year begins. In no year may the amount allocated be less than the total sum required to meet principal and interest payments becoming due to that fiscal year on state school bonds.