partake vs pitch in

partake

verb
  • To take part in an activity; to participate. 

  • To take a share or portion (of or in). 

pitch in

verb
  • To help out; lend assistance; contribute; to do one's part to help. 

  • To begin briskly. 

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