cold cash vs paper money

cold cash

noun
  • Money, especially in the form of paper currency or coins, which is in hand or readily available for use. 

paper money

noun
  • Cash in the form of banknotes. 

  • A type of joss paper resembling banknotes burnt to venerate the deceased, ancestor spirits, deities, etc. 

How often have the words cold cash and paper money occurred in a corpus of books? (source: Google Ngram Viewer )