The comptroller shall distribute money appropriated to the program under this subchapter among the counties as follows:
(1) two-fifths according to total population, determined by the ratio of the total population of the county to the total population of the state;
(2) one-fifth according to population, determined by the ratio of the population in unincorporated areas of the county to the population in all unincorporated areas of the state;
(3) one-fifth according to lineal county road miles, determined by the ratio of lineal mileage of county roads in the county to the lineal mileage of county roads in the state, according to the most recent county road inventory compiled by the Texas Department of Transportation; and
(4) one-fifth according to paved and concrete county road miles, determined by the ratio of miles of lanes of paved and concrete county roads in the county to the miles of lanes of paved and concrete county roads in the state, according to the most recent county road inventory compiled by the Texas Department of Transportation.