pass off vs see the back of

pass off

verb
  • To abate, to cease gradually. 

  • To happen. 

  • To give something (to someone). 

see the back of

verb
  • To be rid of. 

  • Used other than figuratively or idiomatically: see see, back. 

How often have the words pass off and see the back of occurred in a corpus of books? (source: Google Ngram Viewer )