liven up vs pluck up

liven up

verb
  • To become more happy, energetic or positive 

  • To improve a person's mood by making them more energetic 

pluck up

verb
  • To become more cheerful. 

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

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

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