hammer home vs implant

hammer home

verb
  • To repeatedly or continually emphasise (an opinion or idea) until or so that a person or group of people understands it. 

implant

verb
  • To fix firmly or set securely or deeply. 

  • Of an embryo, to become attached to and embedded in the womb. 

  • To insert (something) surgically into the body. 

noun
  • Anything surgically implanted in the body, such as a tissue graft or prosthesis, particularly breast implants. 

  • A representative of a travel company, working within the office of a large client and exclusively dealing with that client. 

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