nationalism vs unionism

nationalism

noun
  • Support for the union of Northern Ireland and the Republic of Ireland. 

  • Support for the creation of a sovereign nation (which does not currently exist). 

  • Patriotism; the idea of supporting one's country, people or culture. 

unionism

noun
  • Support for the continuance of the United Kingdom (especially with respect to Northern Ireland). 

  • The support of advocacy of a union, especially of a trade union. 

  • Support for the North (the Union) during the American Civil War. 

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