The State Board shall regularly update the existing bed inventory and associated bed need projections required by Sections 12 and 12.3 of this Act, using the most recently published historical utilization data, 5-year population projections, and an appropriate migration factor for the medical-surgical and pediatric category of service which shall be no less than 50%. The State Board shall provide written documentation providing the methodology and rationale used to determine the appropriate migration factor.
20 ILCS 3960/12.5