(a) In addition to the dropout rate the department compiles pursuant to the federal No Child Left Behind Act of 2001 (20 U.S.C. Sec. 6301 et seq.), the department shall compile an attrition rate for high school pupils in the state pursuant to the formula specified in subdivision (b).
(b) The attrition rate is the difference between the number of pupils who enrolled in grade 9 in a particular year and the number of pupils who, four years later, receive a diploma of graduation from high school, divided by the number of pupils who enrolled in grade 9 in the particular year.