hold on vs peg away

hold on

verb
  • To persist. 

  • To remain loyal. 

  • To grasp or grip firmly. 

  • To keep; to store something for someone. 

  • Wait a short while. 

peg away

verb
  • To keep working at something 

How often have the words hold on and peg away occurred in a corpus of books? (source: Google Ngram Viewer )