The office shall annually, for purposes of this article, determine a rating of A, B, C, D, or F for each public elementary and secondary school in this state based on student achievement, achievement gap closure, and student growth. Such ratings shall be based on the state accountability system approved by the State Board of Education. (Code 1981, § 20-14-104, enacted by Ga. L. 2015, p. 92, § 1/SB 133.)