cot vs folding bed

cot

noun
  • A cover or sheath; a fingerstall. 

  • A simple bed, especially one for portable or temporary purposes. 

  • A bed for infants or small children, with high, often slatted, often moveable sides. 

  • A wooden bed frame, slung by its corners from a beam, in which officers slept before the introduction of bunks. 

  • A pen, coop, or similar shelter for small domestic animals, such as sheep or pigeons. 

  • A small, crudely-formed boat. 

folding bed

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