enslave vs incarcerate

enslave

verb
  • To make subservient; to strip one of freedom; enthrall. 

incarcerate

verb
  • To lock away; to imprison, especially for breaking the law. 

  • To confine; to shut up or enclose; to hem in. 

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