Every issuer of a group health benefit plan subject to this chapter shall provide a cost report for each calendar year to the Commissioner of Insurance no later than April 30th of the following year. The report shall be in a form prescribed by the commissioner and shall include certification of parity in mental health benefits and total annual costs of mental health services relative to total health costs. The commissioner shall compile this data for all health benefit plans in an annual report solely for the purpose of demonstrating the health cost impact of the requirements of this chapter.