pencil sharpener vs woodchip

pencil sharpener

noun
  • A device used to sharpen pencils by shaving the wood at one end. 

woodchip

noun
  • A small mechanically produced piece (chip) of wood, generally from 0.5 to 10 cm in diameter, used primarily as raw material for pulp, paper and construction boards, as well as fuel and mulch. 

  • A small fibre of wood; especially such material as used to make ingrain wallpaper, aka woodchip wallpaper. See Wikipedia article on ingrain wallpaper. 

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