18-wheeler vs juggernaut

18-wheeler

noun
  • A big rig truck: a semi-trailer plus the truck or tractor pulling it. 

juggernaut

noun
  • A large, cumbersome truck or lorry, especially an artic. 

  • An institution that incites destructive devotion or to which people are carelessly sacrificed. 

  • A literal or metaphorical force or object regarded as unstoppable, that will crush all in its path. 

How often have the words 18-wheeler and juggernaut occurred in a corpus of books? (source: Google Ngram Viewer )