dark as pitch vs murky

dark as pitch

adj

  • Synonym of pitch-dark 

murky

adj

  • Dark, dim, gloomy. 

  • Hard to see through, as a fog or mist. 

  • Cloudy, indistinct, obscure. 

  • Dishonest, shady. 

How often have the words dark as pitch and murky occurred in a corpus of books? (source: Google Ngram Viewer )