promote vs strengthen

promote

verb
  • To encourage, urge or incite. 

  • To increase the activity of (a catalyst) by changing its surface structure. 

  • To elevate to a higher league. 

  • To raise (someone) to a more important, responsible, or remunerative job or rank. 

  • To move on to a subsequent stage of education. 

  • To advocate or urge on behalf of (something or someone); to attempt to popularize or sell by means of advertising or publicity. 

  • To exchange (a pawn) for a queen or other piece when it reaches the eighth rank. 

strengthen

verb
  • To reinforce, to add to, to support (someone or something) 

  • To make strong or stronger; to add strength to; to increase the strength of; to fortify. 

  • To empower; to give moral strength to; to encourage; to enhearten. 

  • To grow strong or stronger. 

  • To substantiate; to corroborate (a belief, argument, etc.) 

  • To augment; to improve; to intensify. 

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