commend vs thank

commend

verb
  • To mention by way of courtesy, implying remembrance and goodwill. 

  • To recommend. 

  • To entrust or commit to the care of someone else. 

  • To praise or acclaim. 

  • To congratulate or reward. 

thank

verb
  • To express gratitude or appreciation toward. 

  • To feel gratitude or appreciation toward. 

  • To credit or hold responsible. 

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