Funds to be paid to the several counties pursuant to RCW 46.68.120(4) shall be allocated among them upon the basis of a distribution formula consisting of the following four factors:

(1) An equal distribution factor of ten percent of such funds shall be paid to each county;

(2) A population factor of thirty percent of such funds shall be paid to each county in direct proportion that the county's total equivalent population, as computed pursuant to RCW 46.68.124(1), is to the total equivalent population of all counties;

(3) A road cost factor of thirty percent of such funds shall be paid to each county in direct proportion that the county's total annual road cost, as computed pursuant to RCW 46.68.124(2), is to the total annual road costs of all counties;

(4) A money need factor of thirty percent of such funds shall be paid to each county in direct proportion that the county's money need factor, as computed pursuant to RCW 46.68.124(3), is to the total of money need factors of all counties.