dirty protest vs occupation

dirty protest

noun
  • A form of protest where a prisoner refuses to use the toilet and instead defecates and urinates within his or her cell. 

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. 

How often have the words dirty protest and occupation occurred in a corpus of books? (source: Google Ngram Viewer )