museum piece vs objet d'art

museum piece

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

objet d'art

noun
  • A work of art with some artistic merit. 

  • An artwork exhibited for the purposes of decoration or the reflection of social status. 

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