quartet vs six

quartet

noun
  • A group of four people or things, particularly 

  • A group of four musicians who perform classical music together. 

  • A group of four singers, usually males, who sings together in four-part harmony. 

  • A musical composition in four parts, each performed by a single voice or instrument. 

six

noun
  • A group or set with six elements. 

  • Rear, behind (rear side of something). 

  • The digit or figure 6. 

  • A touchdown. 

  • An event whereby a batsman hits a ball which does not bounce before passing over a boundary in the air, resulting in an award of 6 runs for the batting team. 

num
  • A numerical value equal to 6; the number following five and preceding seven. This many dots: (••••••). 

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