cover-up vs smokescreen

cover-up

noun
  • An attempt to conceal or disguise something, especially a wrongdoing or a mistake. 

  • An item of clothing to be worn over a swimsuit while not in the water. 

smokescreen

noun
  • Anything used metaphorically to conceal or distract. 

  • Smoke used as a disguise, mask or cover, as of troops in battle. 

How often have the words cover-up and smokescreen occurred in a corpus of books? (source: Google Ngram Viewer )