enforce vs impose

enforce

verb
  • To keep up, impose or bring into effect something, not necessarily by force. 

  • To give strength or force to; to affirm, to emphasize. 

impose

verb
  • to enforce: compel to behave in a certain way 

  • To practice a trick or deception (on or upon). 

  • To arrange in proper order on a table of stone or metal and lock up in a chase for printing; said of columns or pages of type, forms, etc. 

  • To establish or apply by authority. 

  • To lay on, as the hands, in the religious rites of confirmation and ordination. 

  • to be an inconvenience (on or upon) 

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