backing vs concurrence

backing

noun
  • The action of putting something back; a switching into reverse. 

  • Support, especially financial. 

  • A backdrop. 

  • The mounting of a horse or other animal. 

  • A liner or other material added behind or underneath. 

  • Musicians and vocalists who support the main performer. 

adj
  • Providing support for the main performer. 

concurrence

noun
  • An instance of simultaneous occurrence. 

  • Agreement; concurring. 

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