fall flat vs plough into

fall flat

verb
  • To produce no effect; to fail in the intended effect. 

plough into

verb
  • To crash into something. 

  • To engage in some activity with vigor. 

  • To invest a resource (money, material, energy) into something. 

How often have the words fall flat and plough into occurred in a corpus of books? (source: Google Ngram Viewer )