back garden vs esplanade

back garden

noun
  • A garden at the rear of a property. 

esplanade

noun
  • A grass plat; a lawn. 

  • A clear space between a citadel and the nearest houses of the town. 

  • The glacis of the counterscarp, or the slope of the parapet of the covered way toward the country. 

  • Any clear, level space used for public walks or drives; especially, a terrace by the seaside. 

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