goodbye vs what's doing

goodbye

noun
  • An utterance of goodbye, the wishing of farewell to someone. 

verb
  • To say goodbye; to wish somebody farewell on parting. 

intj
  • Farewell; a formula used to another person or persons when the speaker, writer, or person addressed is departing. 

what's doing

phrase
  • An informal greeting. 

How often have the words goodbye and what's doing occurred in a corpus of books? (source: Google Ngram Viewer )