downspout vs rain gutter

downspout

noun
  • A vertical pipe or conduit that carries rainwater from the scupper, guttering of a building to a lower roof level, drain, ground or storm water runoff system. 

rain gutter

noun
  • Any gutter designed to carry away rain, such as an eavestrough on a building or a drain on a motor vehicle's roof rack. 

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