Each insurer and self-insurer under this chapter shall, under regulations prescribed by the board of trustees, make payments to the fund in an amount equal to that proportion of 175 percent of the total disbursement made from the fund during the preceding calendar year less the amount of the net assets in the fund as of December 31 of the preceding calendar year which the total workers' compensation claims paid by the insurer or self-insurer bears to the total workers' compensation claims paid by all insurers and self-insurers during the preceding calendar year. The administrator is authorized to reduce or suspend assessments for the fund when a completed actuarial survey shows further assessments are not needed. An employer who has ceased to be a self-insurer prior to the end of the calendar year shall be liable to the fund for the assessment of the calendar year. The initial assessment of each insurer or self-insurer for the purpose of generating revenue to begin operation of the fund shall be in the amount of one-half of 1 percent of the workers' compensation premiums collected by the insurer for the preceding calendar years from an employer who is subject to this chapter or the equivalent of such in the case of a self-insurer.