common dolphin vs grampus

common dolphin

noun
  • One of two species of dolphin in the genus Delphinus. 

grampus

noun
  • Risso's dolphin, Grampus griseus, with a blunt nose. 

  • The hellbender salamander, Cryptobranchus alleganiensis. 

  • The killer whale, Orcinus orca. 

  • giant whip scorpion (Mastigoproctus giganteus) 

How often have the words common dolphin and grampus occurred in a corpus of books? (source: Google Ngram Viewer )