leadership vs pilotage

leadership

noun
  • The office or status of a leader. 

  • The capacity of someone to lead others. 

  • A group of leaders. 

pilotage

noun
  • The occupation of a pilot. 

  • The use of landmarks to guide a vessel or aircraft to its destination. 

  • The fee paid to a pilot. 

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