call it a day vs shut down

call it a day

verb
  • To cease the activity for the day. 

  • To retire. 

shut down

verb
  • To turn off or stop. 

  • To pass (another vehicle), especially quickly. 

  • To close, terminate, or end. 

  • To emotionally withdraw into oneself as a defense mechanism; to block out external stressors. 

How often have the words call it a day and shut down occurred in a corpus of books? (source: Google Ngram Viewer )