In each year, the commissioner shall ascertain and determine as to each municipality in the State:
(a) The sum total of the net valuation taxable, and the value of the second-class railroad property, therein, as exhibited in the abstract of ratables of the several counties for the preceding year as made out by the State Commissioner of Taxation and Finance and filed in the office of the State Comptroller, which sum total shall be known as the municipalities "preceding year's ratables" ;
(b) The cost of public assistance, exclusive of the cost of administration thereof, for the preceding year therein, which shall be known as the municipalities "preceding year's public assistance load" ;
(c) The cost of public assistance, exclusive of the cost of administration thereof, for the current year therein, which shall be known as the municipalities "current year's public assistance load" ;
(d) The number of mills on each dollar of the "preceding year's ratables" which would have to be levied in each municipality to raise an amount equal to the "preceding year's public assistance load" which millage shall be known as the municipalities "preceding year's public assistance millage."
In determining any municipality's "preceding year's public assistance load" and "current year's public assistance load," the commissioner may include therein the cost to the municipality of public assistance paid or payable by the welfare board of the county.