If at any time it appears to the director or his designee that rates charged for property, casualty, surety, marine, title, or allied lines of insurance in this State are excessive or unreasonable, in that the results of the business of the insurer in this State during the five years immediately preceding the year in which the investigation is made, as indicated by the insurer’s annual statements and any supplements to them, show an aggregate operating profit in excess of a reasonable amount, then the director or his designee may order a general reduction in rates which will reduce the operating profit to a reasonable amount. Any reduction ordered by the director or his designee must be applied to the class or classes of risks as the insurer or rating bureau may elect, and they may not be compelled to reduce rates on classes which have not produced a reasonable operating profit for the five-year period. In addition to ordering a general reduction in rates, the director or his designee may also order a pro rata refund of any excessive or unreasonable profits found to have been realized by the insurer, together with interest. The director or his designee shall determine the rate of interest which must be the insurer’s average rate of return for the five-year period. Any refund which is ordered must be equitably apportioned among the policyholders entitled to it, and may be given either in the form of a cash refund or as a credit toward future premiums or a combination of these two methods. In determining the question of a reasonable operating profit under this section, the director or his designee as a protection to policyholders shall give proper and reasonable consideration to conflagration liabilities, both within and without this State.