negativity vs optimism

negativity

noun
  • The characteristic of being pessimistic or contrarian. 

  • Negative sentiment. 

  • The characteristic of having a negative charge. 

optimism

noun
  • the doctrine that this world is the best of all possible worlds 

  • a tendency to expect the best, or at least, a favourable outcome 

  • the belief that good will eventually triumph over evil 

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