firebrand vs rioter

firebrand

noun
  • An argumentative troublemaker or revolutionary; one who agitates against the status quo. 

  • A torch or other burning stick with a flame at one end. 

rioter

noun
  • One who riots; part of the unruly violent crowd causing a riot. 

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