appreciate vs pat oneself on the back for

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. 

pat oneself on the back for

How often have the words appreciate and pat oneself on the back for occurred in a corpus of books? (source: Google Ngram Viewer )