flash in the pan vs seven-day wonder

flash in the pan

noun
  • A transient occurrence with no long-term effect. 

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

seven-day wonder

noun
  • An individual or a process which requires only seven days to be perfected. 

  • Synonym of nine-day wonder 

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