amenity vs labor-saving device

amenity

noun
  • Pleasantness. 

  • A thing or circumstance that is welcome and makes life a little easier or more pleasant. 

  • Convenience. 

  • a unit pertaining to the infrastructure of a community, such as a public toilet, a postbox, a library, etc. 

labor-saving device

How often have the words amenity and labor-saving device occurred in a corpus of books? (source: Google Ngram Viewer )