Michigan Compiled Laws, Chapter 418. Worker's Disability Compensation § 418.355

Sec. 355. (1) The maximum weekly rate shall be adjusted once each year in accordance with the increase or decrease in the average weekly wage in covered employment, as determined by the Michigan employment security commission.

(2) Effective January 1, 1982, and each January 1 thereafter, the maximum weekly rate of compensation for injuries occurring within that year shall be established as 90% of the state average weekly wage as of the prior June 30, adjusted to the next higher multiple of $1.00.

(3) For the purpose of computing the supplemental benefit under section 352,  1 the state average weekly wage for any injury year shall be the average weekly wage in covered employment determined by the Michigan employment security commission for the 12 months ending June 30 of the preceding year.