shutdown vs shutting down

shutdown

noun
  • The action of stopping operations; a closing, of a computer, business, event, etc. 

  • A statement, insult, etc. that prevents the opponent from replying further. 

  • An autistic response to stress or sensory overload, in which the individual freezes up and becomes silent, motionless, and unresponsive. 

shutting down

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