U-turn vs reversal of policy

U-turn

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. 

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. 

reversal of policy

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