nostrify vs vouchsafe

nostrify

verb
  • To nostrificate; to grant recognition to a degree from a foreign university. 

  • To adopt, accept, or include as part of one's own culture. 

vouchsafe

verb
  • To graciously give, to condescendingly grant a right, benefit, outcome, etc.; to deign to acknowledge. 

  • To receive or accept in condescension. 

  • To disclose or divulge. 

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