proprietorship vs purchasing

proprietorship

noun
  • The state of being a proprietor; ownership 

purchasing

noun
  • An act or process of making a purchase. 

  • A part of an organization that manages such processes 

  • A complex, organized process in large organizations for obtaining goods that may include identification of requirements, approvals, supplier management, negotiation, receipt of goods, and payment. 

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