pluck up vs pluck up one's courage

pluck up

verb
  • To summon positive emotion (especially courage); to muster. 

  • To remove or acquire by plucking from, for example, the ground; to pick up. 

  • To become more cheerful. 

pluck up one's courage

verb
  • To muster the bravery and will to do something. 

How often have the words pluck up and pluck up one's courage occurred in a corpus of books? (source: Google Ngram Viewer )