clock on vs punch in

clock on

verb
  • To record one's time of arrival at work, traditionally by inserting one's card into a timestamping machine. 

  • To begin work at the start of the day or start of one's shift. 

punch in

verb
  • To enter a workplace by punching a timecard. 

  • To score. 

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