There shall be levied each year in each county of the state a tax of not to exceed six (6) mills on the dollar of the assessed valuation of the property in each county for the support and maintenance of the public schools. This tax shall be collected by the county treasurer and disbursed among the school districts within the county as the legislature shall provide. The legislature may authorize boards of trustees of school districts to levy a special tax on the property of the district. The legislature may also provide for the distribution among one (1) or more school districts of any revenue from the special school district property tax in excess of a state average yield, which shall be calculated each year, per average daily membership.