414.082.  Inspection fees, rate determined by director of revenue — petroleum inspection fund created, fees deposited, uses, investment of moneys. — 1.  The fee for the inspection of gasoline, gasoline-alcohol blends, kerosene, diesel fuel, heating oil, aviation turbine fuel, and other motor fuels under this chapter shall be fixed by the director of revenue at a rate per barrel which will approximately yield revenue equal to the expenses of administering this chapter; except that, until December 31, 2016, the rate shall not exceed two and one-half cents per barrel, from January 1, 2017, through December 31, 2021, the rate shall not exceed four cents per barrel, and after January 1, 2022, the rate shall not exceed five cents per barrel.

  2.  Annually the director of the department of agriculture shall ascertain the total expenses for administering sections 414.012 to 414.152 during the preceding year, and shall forward a copy of such expenses to the director of revenue.  The director of revenue shall fix the inspection fee for the ensuing calendar year at such rate per barrel, within the limits established by subsection 1 of this section, as will approximately yield revenue equal to the expenses of administering sections 414.012 to 414.152 during the preceding calendar year and shall collect the fees and deposit them in the state treasury to the credit of the "Petroleum Inspection Fund" which is hereby created.  Beginning July 1, 1988, all expenses of administering sections 414.012 to 414.152 shall be paid from appropriations made out of the petroleum inspection fund.

  3.  The unexpended balance in the fund at the end of each fiscal year shall not be transferred to the general revenue fund of the state, and the provisions of section 33.080 relating to the transfer of funds to the general revenue fund of the state by the state treasurer shall not apply to this fund.

  4.  The state treasurer shall invest all sums in the petroleum inspection fund not needed for current operating expenses in interest-bearing banking accounts or United States government obligations in the manner provided by law.  All yield, increment, gain, interest or income derived from the investment of these sums shall accrue to the benefit of, and be deposited within the state treasury to the credit of, the petroleum inspection fund.