cool as a cucumber vs phlegmatic

cool as a cucumber

adj
  • Calm and composed even in difficult or frustrating situations; self-possessed. 

phlegmatic

adj
  • Not easily excited to action or passion; calm; sluggish. 

  • Generating, causing, or full of phlegm. 

noun
  • One who has a phlegmatic disposition. 

How often have the words cool as a cucumber and phlegmatic occurred in a corpus of books? (source: Google Ngram Viewer )