appreciate vs rue

appreciate

verb
  • To be grateful or thankful for. 

  • To increase in value. 

  • To view as valuable. 

  • To be fully conscious of; understand; be aware of; detect. 

rue

noun
  • Any of various perennial shrubs of the genus Ruta, especially the herb Ruta graveolens (common rue), formerly used in medicines. 

verb
  • To repent of or regret (some past action or event); to wish that a past action or event had not taken place. 

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