line manager vs proprietor

line manager

noun
  • The manager who is directly responsible for an employee. 

proprietor

noun
  • An owner. 

  • A sole owner of an unincorporated business, also called a sole proprietor. 

  • One of the owners of an unincorporated business, a partner. 

  • One or more persons to whom a colonial territory is assigned, like a fief, including its administration. 

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