A level vs bumshoving

A level

noun
  • anal sex. 

  • A non-compulsory examination taken in the final two years in British high schools; the qualification obtained by passing such an exam 

bumshoving

noun
  • Anal sex. 

  • Giving way of the hips during the drive phase. 

How often have the words A level and bumshoving occurred in a corpus of books? (source: Google Ngram Viewer )