stroke of good luck vs windfall

stroke of good luck

windfall

noun
  • Something that has been blown down by the wind. 

  • A fruit that has fallen from a tree naturally, as from wind. 

  • A sudden large benefit; especially, a sudden or unexpected large amount of money, as from lottery or sweepstakes winnings or an unexpected inheritance or gift. 

How often have the words stroke of good luck and windfall occurred in a corpus of books? (source: Google Ngram Viewer )