depress vs light a fire under

depress

verb
  • To make depressed, sad or bored. 

  • To cause a depression or a decrease in parts of the economy. 

  • To press down. 

  • To bring down or humble; to abase (pride, etc.). 

  • To reduce (an equation) in a lower degree. 

light a fire under

verb
  • To motivate or encourage (someone) to start sooner or move faster. 

How often have the words depress and light a fire under occurred in a corpus of books? (source: Google Ngram Viewer )