dago vs nig-nog

dago

noun
  • A person of Italian descent. 

  • A person of Italian, Spanish, Portuguese, Greek, or other Mediterranean descent. 

nig-nog

noun
  • A person of color, especially, a black person. 

  • A foolish person; hence, a raw and unskilled recruit. 

How often have the words dago and nig-nog occurred in a corpus of books? (source: Google Ngram Viewer )