pluck up vs summon up

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. 

summon up

verb
  • To look within oneself to find and put into action a particular positive quality, such as strength, energy or courage. 

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