sidewalk vs zebra crossing

sidewalk

noun
  • (usually) a paved footpath located at the side of a road, for the use of pedestrians 

  • any paved footpath, even if not located at the side of a road 

zebra crossing

noun
  • A pedestrian crossing featuring broad white stripes painted parallel to the street. 

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