duo vs trio

duo

noun
  • Any cocktail consisting of a spirit and a liqueur. 

  • Two people who work or collaborate together as partners; especially, those who perform music together. 

  • Any pair of two people. 

  • A song in two parts; a duet. 

trio

noun
  • Any cocktail made with a spirit, a liqueur, and a creamy ingredient. 

  • A piece of music written for three musicians. 

  • A group of three musicians. 

  • A group of three people or things. 

  • A passage in the middle of a minuet, frequently in a different key. 

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