rip off vs sell someone down the river

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. 

sell someone down the river

How often have the words rip off and sell someone down the river occurred in a corpus of books? (source: Google Ngram Viewer )