janitor vs street sweeper

janitor

noun
  • Someone who looks after the maintenance and cleaning of a public building. 

  • A caretaker or custodian; someone who maintains a school building specifically and may serve other administrative roles. 

  • A doorman. 

  • A moderator for a discussion forum. 

street sweeper

noun
  • A person who is employed to sweep streets, pavements, and gutters, keeping them clear of litter. 

  • A machine used to sweep streets. 

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