U-turn vs backflip

U-turn

noun
  • A reversal of policy; an about-face, a backflip. 

  • A turn in a vehicle carried out by driving in a semicircle in order to travel in the opposite direction. 

verb
  • To shift from one opinion or decision to its opposite. 

  • To turn a vehicle in a semicircle so as to face the opposite direction. 

backflip

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

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

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

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

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