picketing vs walkout

picketing

noun
  • The act of one who pickets (in any sense). 

walkout

noun
  • A similar mass action of people leaving a place as a form of protest. 

  • A sudden stoppage of work. 

  • A part of the squat exercise wherein one has to step out from the rack (“walk out” the weight) in order not to hit it during execution. 

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