assume vs take on

assume

verb
  • To take on a position, duty or form 

  • To receive, adopt (a person) 

  • To adopt a feigned quality or manner; to claim without right; to arrogate 

  • To authenticate by means of belief; to surmise; to suppose to be true, especially without proof 

  • To adopt (an idea or cause) 

take on

verb
  • To assume or take responsibility for. 

  • To (attempt to) dribble round (an opposition player). 

  • To catch on, do well; to become popular. 

  • To obtain the services of (a person) in exchange for remuneration; to give someone a job. 

  • To begin to have or exhibit. 

  • To attempt to fight, compete with, or engage with. 

  • To acquire, bring in, or introduce. 

  • To grieve or be concerned (about something or someone). 

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