appreciate vs take on board

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. 

take on board

verb
  • To accept a new idea or piece of advice, and act accordingly. 

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