heirloom vs museum piece

heirloom

noun
  • A valued possession that has been passed down through the generations. 

  • An old crop variety that has been passed down through generations of farmers by seed saving and cultivation, in contrast to modern cultivars used in large-scale agriculture. 

museum piece

noun
  • A very old item, especially an obsolete piece of technology. 

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