fill in vs fill up

fill in

verb
  • To complete a form or questionnaire with requested information. 

  • To substitute for somebody or something. 

  • To beat up; to physically assault. 

  • To fill; to replace material that is absent or has been removed. 

  • To inform somebody, especially to supply someone missing or missed information. 

fill up

verb
  • To fill in / fill out a form etc. 

  • To satisfy the hunger of (someone). 

  • To annoy, or displease, by taunting, or by excessive nagging. 

  • To fill the tank of a vehicle with fuel. 

  • To become completely full. 

  • To make (something) completely full. 

  • To become tearful as a result of strong emotion. 

  • To make a full house on the turn or the river. 

  • To satisfy one's hunger; to stop being hungry. 

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