pocket change vs small change

pocket change

noun
  • An insignificant amount of money. 

small change

noun
  • A minor or insignificant amount of money. 

  • Coins of little value kept in one's pocket or bag. 

  • A person or thing of little importance or value. 

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