suffer vs undergo

suffer

verb
  • To endure, undergo. 

  • To become worse. 

  • To undergo hardship. 

  • To feel pain. 

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 suffer and undergo occurred in a corpus of books? (source: Google Ngram Viewer )