mitigate vs unbar

mitigate

verb
  • To downplay. 

  • To reduce, lessen, or decrease; to make less severe or easier to bear. 

unbar

verb
  • To remove a prohibition. 

  • To remove an impediment that obstructs the passage of (someone or something). 

  • To unlock or unbolt a door that had been locked or bolted with a bar. 

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