fire in the belly vs yen

fire in the belly

noun
  • The emotional stamina and vigor, passion, or inner drive to achieve something, to take action, etc. 

yen

noun
  • A strong desire, urge, or yearning. 

  • The unit of Japanese currency (symbol: ¥) since 1871, divided into 100 sen. 

  • Opium. 

  • A coin or note worth one yen. 

verb
  • To have a strong desire for. 

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