hassock vs zabuton

hassock

noun
  • A thick cushion used as a seat; an ottoman or pouffe. 

  • A cushion used primarily in churches for kneeling on while praying. 

  • A dense clump of grass or vegetation; a tussock. 

zabuton

noun
  • A Japanese cushion for sitting. 

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