assist vs get behind

assist

verb
  • To help. 

  • To make a pass that leads directly towards scoring. 

  • To help compensate for what is missing with the help of a medical technique or therapy. 

noun
  • A decisive pass made to the goal scorer 

  • A helpful action or an act of giving. 

  • A defensive play, allowing a teammate to record a putout. 

get behind

verb
  • To support, to cheer on. 

  • To have a trip or any pleasurable experience with drugs. 

  • To come to believe something; to change one's mind into a new position. 

  • To appreciate, to enjoy. 

  • Used other than figuratively or idiomatically: see get, behind. 

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