PM vs premier

PM

verb
  • To project manage. 

  • To send a private message to (a participant in a chat room, etc.). 

premier

verb
  • To govern in the role of premier. 

  • To perform, display or exhibit for the first time. 

noun
  • The champion team of a particular season (especially as used in Australian rules football). 

  • The government leader in a legislative congress or leader of a government-level administrative body; the head of government. 

  • The leader of a state or provincial government and cabinet. 

  • The prime minister. 

  • The first lieutenant or other second-in-command officer of a ship. 

adj
  • Most ancient. 

  • Foremost; first or highest in quality or degree. 

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