educational institution vs polytechnic

educational institution

noun
  • A place where people of different ages gain an education, including preschools, childcare, elementary schools, and universities. 

polytechnic

noun
  • A three-year post-secondary vocational training institute, equivalent of community college in the U.S. or TAFE in Australia. 

adj
  • that teaches applied arts, sciences, technology, engineering and other academic subjects 

How often have the words educational institution and polytechnic occurred in a corpus of books? (source: Google Ngram Viewer )