Britain vs the UK

Britain

name
  • 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 United Kingdom. 

  • The British Empire. 

the UK

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