Any producer or importer whose total sales of flowers and plants do not exceed $100,000 during a twelve consecutive month period prior to the date an assessment is due and payable shall be exempt from assessments under this chapter under such conditions and procedures as may be prescribed in the order or rules and regulations issued thereunder and shall not vote in any referendum under this chapter: Provided, That the Floraboard shall have the discretion to make annual adjustments in the level of exemption to account for inflation. For the purpose of this section, a producer’s or importer’s total sales shall include, in those cases in which the producer or importer is an individual, sales attributable to such person’s spouse, children, grandchildr