(2) The superintendent shall compute a per pupil amount from the balance of the appropriation provided by subdivision (b) of Section 4 of the act adding this section, after the appropriation has been reduced by the amounts in paragraph (1), by dividing the remaining portion of the appropriation by the total average daily attendance, excluding attendance for regional occupational centers and programs, adult education, and programs operated by the county superintendents of schools, for all pupils in kindergarten through grade 12 in all school districts as used by the Superintendent of Public Instruction for the second principal apportionment for the 1999-2000 fiscal year. The superintendent shall apportion to each school district an amount equal to the per pupil amount times the district's reported average daily attendance for the second principal apportionment for the 1999-2000 fiscal year, excluding attendance for regional occupational centers and programs, adult education, and programs operated by the county superintendent of schools.