whet vs work up

whet

verb
  • To stimulate or make more keen. 

  • To hone or rub on with some substance, as a piece of stone, for the purpose of sharpening – see whetstone. 

noun
  • The act of whetting something. 

  • That which whets or sharpens; especially, an appetizer. 

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 whet and work up occurred in a corpus of books? (source: Google Ngram Viewer )