bivvy vs camping

bivvy

noun
  • A small tent or shelter. 

verb
  • To erect, or to stay in, such a tent or shelter. 

camping

noun
  • The recreational activity of temporarily living in a tent or similar accommodation, usually in the wilderness. 

  • The act of setting up a camp. 

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