lanugo vs netherhair

lanugo

noun
  • Soft down or fine hair, specifically that covering the human foetus or a tumorous area. 

netherhair

noun
  • Hair on or around the lower parts of the body, specifically around the genital areas; pubic hair. 

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