caoutchouc vs latex

caoutchouc

noun
  • latex; natural rubber 

latex

noun
  • Natural latex rubber, especially non-vulcanized rubber, such as is used in making latex gloves, latex condoms, and latex clothing. 

  • An emulsion of rubber in water, used in adhesives and the like. 

  • The milky sap of several trees that coagulates on exposure to air; used to make rubber. 

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