safe-deposit box vs treasure chest

safe-deposit box

noun
  • A fireproof metal box, stored in a secure vault, for holding personal valuables 

treasure chest

noun
  • A chest filled with treasure, especially one used by pirates, etc. 

  • Any source of something valuable or beautiful. 

  • A treasury, especially a state or royal treasury. 

How often have the words safe-deposit box and treasure chest occurred in a corpus of books? (source: Google Ngram Viewer )