balls of steel vs temerity

balls of steel

noun
  • Courage, audacity. 

temerity

noun
  • Reckless boldness; foolish bravery. 

  • An act or case of reckless boldness. 

  • Effrontery; impudence. 

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