Premium rates charged for pool coverage may not be unreasonable in relation to the benefits provided, the risk experience, and the reasonable expenses of providing the coverage. Rates shall directly relate to the coverage provided, risk experience, and expenses of providing the coverage. Rates and rate schedules may be adjusted for appropriate risk factors such as age, sex, and area variation in claim costs in accordance with established actuarial and underwriting practices. The pool shall determine the standard risk rate by calculating the average individual rate charged by the five insurers writing the largest amount of individual health insurance coverage in the state actuarially adjusted to be comparable with the pool coverage. In the event five insurers do not offer comparable coverage, the standard risk rate shall be established using reasonable actuarial techniques and shall reflect anticipated risk experience and expenses for such coverage. The annual premium rate established for pool coverage shall be one hundred thirty-five percent of rates established as applicable for individual standard risks. The board shall not adjust or increase pool rates more than one time during any calendar year. All rates and rate schedules shall be submitted to the director for approval. The director shall hold a public hearing pursuant to the Administrative Procedure Act prior to approving an adjustment to or increase in pool rates.