ersatz vs make believe

ersatz

noun
  • Something made in imitation; an effigy or substitute. 

adj
  • Made in imitation; artificial, especially of a poor quality. 

make believe

noun
  • The act of pretending that what is imaginary is real. 

verb
  • To pretend or imagine. 

adj
  • imaginary; conjured in someone's imagination, especially when imagined by a child 

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