catch fire vs set afire

catch fire

verb
  • To become engulfed in flames, to combust. 

  • To become very popular or widespread; to take off. 

  • To be inspired by passion or zeal. 

set afire

verb
  • Synonym of set on fire 

How often have the words catch fire and set afire occurred in a corpus of books? (source: Google Ngram Viewer )