resign vs retain

resign

verb
  • To hand over (something to someone), place into the care or control of another. 

  • To quit (a job or position). 

  • To submit passively; to give up as hopeless or inevitable. 

  • To give up; to relinquish ownership of. 

retain

verb
  • To keep in possession or use. 

  • To employ by paying a retainer. 

  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To keep in one's pay or service. 

  • To hold secure. 

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