auburn vs dirty blonde

auburn

adj
  • Of a reddish-brown colour. 

noun
  • A dark reddish-brown colour, often used to describe hair colour. 

dirty blonde

adj
  • Of a dark blonde colour/color bordering on light brown. 

noun
  • A dark shade of blonde, bordering on light brown. 

  • A person with dark blonde hair. 

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