Britain vs Kingdom of Great Britain

Britain

name

  • The United Kingdom. 

  • Brittany. 

  • The British Isles. 

  • The island of Great Britain, consisting of England, Scotland and Wales, especially during antiquity. 

  • The British state and its dominions and holdings; the British Empire. 

  • The British Empire. 

Kingdom of Great Britain

name

  • The name of the United Kingdom from 1707-1801. 

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