calm down vs cool off

calm down

verb
  • To cause to become less excited, intense, or angry. 

  • To become less excited, intense, or angry. 

cool off

verb
  • To cause to decrease in temperature, activity or temper. 

  • To decrease in temperature, activity, or temper. 

How often have the words calm down and cool off occurred in a corpus of books? (source: Google Ngram Viewer )