encourage vs put a damper on

encourage

verb
  • To mentally support; to motivate, give courage, hope or spirit. 

  • To spur on, strongly recommend. 

  • To foster, give help or patronage 

put a damper on

verb
  • To stop people from enjoying an activity. 

How often have the words encourage and put a damper on occurred in a corpus of books? (source: Google Ngram Viewer )