septette vs sextet

septette

noun
  • A musical composition for seven instruments or seven voices; a septuor. 

  • A set of seven persons or objects. 

sextet

noun
  • A composition for six voices or instruments. 

  • Any group of six people or things. 

  • A group of six singers or instrumentalists. 

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