Sec. 2. In making the annual per capita apportionment to the schools of the counties having a population of not less then twenty-nine thousand, seven hundred and fifty (29,750) and not more than thirty thousand and twenty-five (30,025) the County School Trustees shall make an annual allowance out of the State and County Available Funds for the payment of the salary of the Superintendent of Public Instruction not less than Three Thousand, Six Hundred Dollars ($3,600).