drop out vs stand down

drop out

verb
  • To be lost or momentarily interrupted. 

  • To leave (school, a race, etc.) prematurely and voluntarily. 

  • Used other than figuratively or idiomatically: see drop, out. 

  • To opt out of conventional society. 

stand down

verb
  • To wait; to stop pursuing, stop fighting, or relax from a heightened readiness posture. 

  • To withdraw or retire from a position or from a team. 

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