Funds to be paid to the counties of the state shall be subject to deduction and distribution as follows:
(1) One and one-half percent of such funds shall be deducted monthly as such funds accrue and set aside for the use of the department of transportation and the county road administration board for the supervision of work and expenditures of such counties on the county roads thereof, including the supervision and administration of federal-aid programs for which the department of transportation has responsibility: PROVIDED, That any funds so retained and not expended shall be credited in the succeeding biennium to the counties in proportion to deductions herein made;
(2) All sums required to be repaid to counties composed entirely of islands shall be deducted;
(3) Thirty-three one-hundredths of one percent of such funds shall be deducted monthly, as such funds accrue, and set aside for the use of the department of transportation for the purpose of funding the counties' share of the costs of highway jurisdiction studies and other studies. Any funds so retained and not expended shall be credited in the succeeding biennium to the counties in proportion to the deductions made;
(4) The balance of such funds remaining to the credit of counties after such deductions shall be paid to the several counties monthly, as such funds accrue, in accordance with RCW
46.68.122 and
46.68.124.