The State Board of Education shall direct that apportionment grants for teacher aide projects be made to school districts on the basis of two thousand dollars ($2,000) per school year per teacher aide employed, diminished by an amount derived by multiplying the ratio which the assessed valuation per unit of average daily attendance during the preceding fiscal year in grades kindergarten through eight in the district bears to the assessed valuation per unit of such average daily attendance in the state times one thousand dollars ($1,000).