bluffing vs slyness

bluffing

noun
  • A bluff; a false expression of the strength of one's position in order to intimidate. 

slyness

noun
  • The result or product of being sly. 

  • The state or quality of being sly. 

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