back away vs pull back

back away

verb
  • To move in a direction opposite to that which one is facing, keeping one's attention on the thing in front being avoided. 

pull back

verb
  • Used other than figuratively or idiomatically: see pull, back. 

  • To retreat. 

  • To pass (the ball) into a position further from the attacking goal line. 

  • To score when the team is losing. 

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