live off the backs of vs rip off

live off the backs of

rip off

verb
  • To steal, cheat or swindle. Especially to charge an exorbitant or unfair rate. 

  • To pull off by ripping 

  • To copy, especially illegally. 

How often have the words live off the backs of and rip off occurred in a corpus of books? (source: Google Ngram Viewer )