nouveau riche vs zillionaire

nouveau riche

noun
  • New money; wealthy persons whose fortunes are newly acquired, and who are therefore perceived to lack the refinement of those who were raised wealthy. 

adj
  • Newly rich; like a nouveau riche. 

zillionaire

noun
  • An incredibly rich person. 

How often have the words nouveau riche and zillionaire occurred in a corpus of books? (source: Google Ngram Viewer )