For claims of an insured which total at least one hundred thousand dollars and not more than one million dollars incurred per plan year, a member insurer must be reinsured by the association at an amount not exceeding seventy-five percent of the member insurer's responsibility for claims incurred by the insured pursuant to the terms of an individual health benefit plan. The board shall annually determine the attachment points and coinsurance percentage for association claims for each plan year on or before April first of the preceding year.