setback vs stroke of bad luck

setback

noun
  • An offset to the temperature setting of a thermostat to cover a period when more or less heating is required than usual. 

  • An obstacle, delay, disadvantage, blow (an adverse event which retards or prevents progress towards a desired outcome) 

  • A step-like recession in a wall. 

  • The required distance between a structure and a road. 

stroke of bad luck

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