tolerate vs undergo

tolerate

verb
  • To bear, withstand. 

  • To allow or permit without explicit approval, usually if it is perceived as negative. 

undergo

verb
  • To suffer or endure; bear with. 

  • To experience; to pass through a phase. 

  • The project is undergoing great changes. 

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