Oregon Revised Statutes Highways, Roads, Bridges and Ferries § 366.764

The sum designated in ORS 366.762 shall be remitted by warrant to the county treasurers of the several counties. The remittance in any year shall be in proportion of the number of vehicles, trailers, semitrailers, pole trailers and pole or pipe trailers registered in each county, to the total number of such vehicles registered in the state as of December 31 of the preceding year, as indicated by motor vehicles registration records. All such vehicles owned and operated by the state and registered under ORS 805.040, 805.045 and 805.060 shall be excluded from the computation in making the apportionment.