comprehensive school vs middle school

comprehensive school

noun
  • a normal secondary school, accepting pupils of all abilities; replaced the secondary modern schools and grammar schools 

middle school

noun
  • A school which crosses the traditional divide between primary school and secondary school. 

  • An educational level or stage between primary school and secondary school. 

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