mantelpiece vs plinth

mantelpiece

noun
  • A shelf that is affixed to the wall above a fireplace. 

plinth

noun
  • A base or pedestal beneath a cabinet. 

  • A block or slab upon which a column, pedestal, statue or other structure is based. 

  • The bottom course of stones or bricks supporting a wall. 

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