Z vs zee

Z

noun
  • Z-drug. 

  • A member of Generation Z. 

character
  • The twenty-sixth letter of the English alphabet, called zed or zee and written in the Latin script. 

zee

noun
  • Something Z-shaped. Found in compounds. 

  • Sleep. 

  • The name of the Latin-script letter Z. 

verb
  • To zigzag; to move with sharp alternating turns. 

  • To sleep or nap. (Compare zzz, catch some z's.) 

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