plummet vs road accident

plummet

noun
  • A violent or dramatic fall. 

  • A decline; a fall; a drop. 

verb
  • To drop swiftly, in a direct manner; to fall quickly. 

road accident

noun
  • A collision on a road, typically involving one or more motor vehicles, but also including cyclists and pedestrians knocked down by vehicles. 

How often have the words plummet and road accident occurred in a corpus of books? (source: Google Ngram Viewer )