abstention vs denialism

abstention

noun
  • The act of declining to vote on a particular issue. 

  • Non-participation in the political world; as a country avoiding international affairs. 

  • The act of abstaining or refraining (from). 

denialism

noun
  • The practice of rejecting propositions which are strongly supported by scientific or historical evidence, and often of seeking to influence policy processes and outcomes accordingly. 

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