instigate vs work up

instigate

verb
  • to incite; to bring about by urging or encouraging 

  • to goad or urge (a person) forward, especially to wicked actions; to provoke 

work up

verb
  • To raise; to excite; to stir up. 

  • To give (a patient) a general medical examination to assess health and fitness. 

  • To develop. 

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