about turn vs backflip

about turn

noun
  • A complete change of opinion, direction, etc. 

  • Of a formation of soldiers, to reverse the direction in which they are facing; an about face. 

verb
  • To turn to face the opposite direction. 

backflip

noun
  • a total reversal in policy or opinion; a volte-face, a U-turn. 

  • An act of rotating one's body 360 degrees in the backward direction. 

verb
  • To perform a backflip (rotation of body). 

  • To completely reverse a policy or opinion; perform a U-turn. 

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