layman vs man on the Clapham omnibus

layman

noun
  • 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. 

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

man on the Clapham omnibus

noun
  • Any ordinary person; everyman. 

  • Any hypothetical reasonable person used by the Courts in considering questions of reasonableness; everyman. 

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