pensiveness vs preoccupation

pensiveness

noun
  • A thoughtful or reflective state, especially if sad or melancholic. 

preoccupation

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

  • The act of occupying something before someone else. 

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