(a) The director of taxation is entitled to demand and receive from the manufacturer, importer, exporter or distributor first selling, offering for sale, using or delivering gasoline or diesel including government sales, the sum of $.015 per barrel. For the purposes of this section 50 gallons is to be considered and counted as a barrel.

(b) The secretary is hereby authorized and empowered to reduce the fees and charges provided by subsection (a) for any period deemed justified whenever the secretary shall determine that such fees and charges being paid into the state treasury as required by law are yielding more revenue than is required for the purposes to which such fees and charges are devoted by law. In the event that the secretary determines that sufficient revenues are not being produced by such reduced fees and charges, the secretary is hereby authorized and empowered to restore the fees and charges in full or in part to a rate not exceeding that provided in subsection (a) that will in the secretary’s judgment produce sufficient revenue for the purposes to which such fees and charges are devoted by law.