lick one's chops vs yen

lick one's chops

verb
  • To anticipate something eagerly. 

  • To use one's tongue to remove moistness from the sides of one's mouth, as when salivating or at the conclusion of a meal. 

  • To look forward avidly to eating something. 

yen

verb
  • To have a strong desire for. 

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. 

How often have the words lick one's chops and yen occurred in a corpus of books? (source: Google Ngram Viewer )