In 2015, 24% completed secondary school, 22% completed high school[1] (3 years between secondary and undergraduate education), 19% completed graduate/undergraduate education (university, technical colleges, etc.), 6% reported no formal education, and the remaining (14%) reported uncompleted primary or secondary school (some years attended but not graduated/finished) (INEGI, 2015b). On average, population 15 years and older in Mexico have 9.2 years of schooling, which would be equivalent to completing secondary education school and 93.6% of this same age group knows how to read and write (literacy).

[1] Starting in 2018, public compulsory education in Mexico comprises preschool (3 years, starting at age 3), primary education (6 years) and secondary education (3 years). For those 15 years and older at the time of the Inter-Census, compulsory education was comprised of primary (6 years) and secondary (3 years) education.

References:

INEGI. (2015b). Encuesta Intercensal 2015 Estados Unidos Mexicanos. Instituto Nacional de Estadística y Geografía, 1, 85–90. http://internet.contenidos.inegi.org.mx/contenidos/Productos/prod_serv/contenidos/espanol/bvinegi/productos/nueva_estruc/702825078966.pdf