(a) For mortgage guaranty insurance in force prior to January 11, 1995, no more than 25 percent of the total liability, net of reinsurance, of a mortgage insurance company shall be mortgage pool insurance.

(b) For the purpose of subdivision (a) of this section, total liability shall be computed on the basis of the aggregate loss limit in a policy providing mortgage pool insurance coverage.

(c) In any pool insurance policy written by a mortgage insurer prior to January 11, 1995, the total amount at risk on any one pool shall not at any time exceed 20 percent of the outstanding principal balance of mortgage loans insured as stated in the mortgage pool policy.

(d) In any pool insurance policy written by a mortgage insurer on or after January 11, 1995, the total amount at risk on any one pool shall not at any time exceed 25 percent of the outstanding principal balance of mortgage loans insured, as stated in the mortgage pool policy.