Bluegrass State vs Corn-cracker State

Bluegrass State

name

  • The official nickname for the state of Kentucky in the United States of America. 

Corn-cracker State

name

  • An unofficial nickname for the state of Kentucky in the United States of America. 

How often have the words Bluegrass State and Corn-cracker State occurred in a corpus of books? (source: Google Ngram Viewer )