constrain vs favor

constrain

verb
  • To force physically, by strong persuasion or pressuring; to compel; to oblige. 

  • To keep within close bounds; to confine. 

  • To reduce a result in response to limited resources. 

favor

verb
  • To encourage, conduce to 

  • To resemble; especially, to look like (another person). 

  • To do a favor [noun sense 1] for; to show beneficence toward. 

  • To look upon fondly; to prefer. 

  • To use more often. 

  • To treat with care. 

noun
  • A small gift; a party favor. 

  • Mildness or mitigation of punishment; lenity. 

  • A kind or helpful deed; an instance of voluntarily assisting (someone). 

  • Partiality; bias 

  • Goodwill; benevolent regard. 

  • The object of regard; person or thing favoured. 

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