mitch vs sag off

mitch

verb
  • To be absent from school without a valid excuse; to play truant. 

  • To pretend poverty. 

  • John said he was going to mitch the last lesson today. 

  • To pilfer; filch; steal. 

  • To shrink or retire from view; lurk out of sight; skulk. 

  • To grumble secretly. 

sag off

verb
  • To skive; to fail to attend school when required to do so. 

  • Used other than figuratively or idiomatically: see sag, off. 

  • To back off from an opponent against whom one is defending. 

  • To move too far leeward when sailing on the wind. 

  • To fall in share price. 

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