layman vs nonprofessional

layman

noun
  • Someone who is not a professional in a given field. 

  • A common person. 

  • Layperson, someone who is not an ordained cleric or member of the clergy. 

  • A generally ignorant person. 

  • Lay-sister or lay-brother, person received into a convent of monks, following the vows, but not being member of the order. 

  • A person who is untrained or lacks knowledge of a subject. 

nonprofessional

noun
  • One who is not a professional; an amateur. 

adj
  • not professional; amateur 

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