merchant vessels vs shipping

merchant vessels

shipping

noun
  • The transportation of goods. 

  • The body of ships belonging to one nation, port or industry; ships collectively. 

  • Passage or transport on a ship. 

  • Navigation. 

  • The cost of sending an item or package via postal services. 

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