make a mountain out of a molehill vs play down

make a mountain out of a molehill

verb
  • To treat a problem as greater than it is; to blow something out of proportion; to exaggerate the importance of something trivial. 

play down

verb
  • To make or attempt to make something seem less important, likely, or obvious. 

How often have the words make a mountain out of a molehill and play down occurred in a corpus of books? (source: Google Ngram Viewer )