preoccupation vs speculative fiction

preoccupation

noun
  • The act of occupying something before someone else. 

  • The state of being preoccupied or an idea that preoccupies the mind; enthrallment. 

speculative fiction

noun
  • A particular work belonging to this class. 

  • A class of fiction involving fantastic, supernatural or futuristic elements, including fantasy, horror, and science fiction, dealing with worlds, themes, and characters not part of everyday life. 

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