junior high school vs secondary school

junior high school

noun
  • A school for children who have completed elementary school or grade school, but are not yet old enough for high school. In the US, it often includes grades 7 and 8, and possibly also 6 or 9. 

secondary school

noun
  • Middle school; junior high school; a school that one attends between the ages of 12-17 (equivalent of grades 7-10 in North America, and years 7-10 in Australia). 

  • School with education level between primary school and university. 

  • In the UK and Ireland, a state school attended between the ages of 11 and 16 or 18. 

  • The federally designated, graduation-separated classification of grades 9–12 (approximately ages 14–18), regardless of whether they are compiled together in one school or separate from the other grades. 

How often have the words junior high school and secondary school occurred in a corpus of books? (source: Google Ngram Viewer )