The commission shall investigate the needs of soft tree fruit producers, the condition of the markets, and extent to which the same require advertising and research. If the investigation shows that the revenue from the assessments levied is inadequate to accomplish the objects of this chapter, it shall report its findings to the director, showing the necessities of the industry, the probable cost of the required program, and the probable revenue from the existing levy. It may then increase the assessments to be levied to an amount not exceeding two dollars per each two thousand pounds (net weight) of such fruits so contained or packed.