AWOL vs absence without leave

AWOL

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. 

adj
  • Absent without official leave (permission). 

absence without leave

noun
  • The military offense of not being present when expected without proper authority. 

How often have the words AWOL and absence without leave occurred in a corpus of books? (source: Google Ngram Viewer )