expose vs make known

expose

verb
  • To reveal, uncover, make visible, bring to light, introduce (to). 

  • To submit to an active (mostly dangerous) substance like an allergen, ozone, nicotine, solvent, or to any other stress, in order to test the reaction, resistance, etc. 

  • To make available to other parts of a program, or to other programs. 

  • To abandon, especially an unwanted baby in the wilderness. 

  • To subject photographic film to light thereby recording an image. 

make known

verb
  • To disclose (a secret). 

  • To announce (some information) generally. 

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