Sitzfleisch vs rear end

Sitzfleisch

noun
  • A person's bottom; the posterior. 

  • The ability to endure or carry on with an activity. 

rear end

noun
  • The back or hindmost part of anything, such as a car. 

  • The buttocks. 

How often have the words Sitzfleisch and rear end occurred in a corpus of books? (source: Google Ngram Viewer )