downfall vs flash in the pan

downfall

noun
  • A precipitous decline in fortune; death or rapid deterioration, as in status or wealth. 

  • The cause of such a fall; a critical blow or error. 

  • An act of falling down. 

verb
  • To fall down; deteriorate; decline. 

flash in the pan

noun
  • A career notable for early success not followed by significant accomplishment. 

  • A transient occurrence with no long-term effect. 

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