Caddy vs shitbox

Caddy

noun
  • A Cadillac car. 

shitbox

noun
  • An old and decrepit automobile. 

  • A contemptible person. 

  • A dump; a run-down, messy or disgusting item. 

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