frosh vs seventh grade

frosh

noun
  • A first-year student, at certain universities, and a first-or-second-year student at other universities. 

  • A frog. 

verb
  • To initiate academic freshmen, notably in a testing way. 

  • To damage through incompetence. 

seventh grade

noun
  • The period in school that comes after sixth grade and before eighth grade. 

How often have the words frosh and seventh grade occurred in a corpus of books? (source: Google Ngram Viewer )