dependence vs pessimism

dependence

noun
  • The state of being dependent, of relying upon another. 

  • An irresistible physical or psychological need, especially for a chemical substance. 

pessimism

noun
  • A general belief that bad things will happen. 

  • The condition of being pessimal. 

  • The doctrine that this world is the worst of all possible worlds. 

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