occupation vs work-to-rule

occupation

noun
  • The act, process or state of possessing a place. 

  • The control of a country or region by a hostile military and/or paramilitary force. 

  • An activity or task with which one occupies oneself; usually specifically the productive activity, service, trade, or craft for which one is regularly paid; a job. 

work-to-rule

noun
  • A labor protest in which employees do only the minimum work required by the rules of a workplace, following safety or other regulations to the letter in order to cause a slowdown. 

adj
  • Of or pertaining to such a protest. 

How often have the words occupation and work-to-rule occurred in a corpus of books? (source: Google Ngram Viewer )