dependence vs obsession

dependence

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

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

obsession

noun
  • An activity or entity that inspires a compulsive and potentially unhealthy fixation, or the fixation thereby inspired. 

  • An idea that engenders a compulsive or irrational preoccupation, or the preoccupation thereby engendered. 

  • The quality of being obsessed. 

  • Influence or control by evil spirits without possession. 

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