Laser vs thill

Laser

noun
  • A simple type of dinghy 

thill

noun
  • One of the two long pieces of wood, extending before a vehicle, between which a horse is hitched; a shaft. 

  • The shallow stratum of underclay that lies under a seam of coal; the bottom of a coal-seam. 

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