AWOL vs playing hooky

AWOL

adj
  • Absent without official leave (permission). 

noun
  • Absence without proper authority from the properly appointed place of duty, or from unit, organization, or other place of duty at which one is required to be at the time prescribed. 

  • Someone or something missing. 

  • A person who holds AWOL status. 

  • Somebody who is absent without permission. 

playing hooky

How often have the words AWOL and playing hooky occurred in a corpus of books? (source: Google Ngram Viewer )