ethnarch vs helmsman

ethnarch

noun
  • A leader of an ethnic community, especially a Jewish or (in the Ottoman Empire) Eastern Orthodox leader having political as well as spiritual authority. 

  • The governor of a Jewish province under the Roman Empire. 

helmsman

noun
  • A leader. 

  • A member of a ship's crew who is responsible for steering. 

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