Whenever real property within a school district is acquired for state highway purposes, the Superintendent of Public Instruction shall allow to the school district an amount of severance aid as provided in this section, in addition to any other allowances provided by this chapter. For the five years following the acquisition of such property the Superintendent of Public Instruction shall allow to the school district severance aid based on the amount of tax revenues the school district would have received from such property if there had been no such acquisition, computed as follows: for the year following such acquisition, the district shall be allowed the amount of tax revenues, except revenues for bond interest and redemption, which would have been paid during the year of acquisition if the taxes assessed on the property acquired were then paid in full; for the second year the district shall be allowed 80 percent of such amount; for the third year the district shall be allowed 60 percent of such amount; for the fourth year the district shall be allowed 40 percent of such amount; and for the fifth year the district shall be allowed 20 percent of such amount.