Mich. Comp. Laws § 500.2021

Sec. 2021. An unfair method of competition and an unfair or deceptive act or practice in the business of insurance includes failure by a rating organization and an insurer that makes its own rates, within a reasonable time after receiving written request for the information and on payment of a reasonable charge, to furnish to an insured affected by a rate made by it, or to the insured authorized representative, all pertinent information to the rate. Pertinent information under this section does not include information that is a trade secret as determined by the director under section 2108(5) or 2406(6).