heat of passion vs oppression

heat of passion

noun
  • An outburst of anger that leads one to commit a criminal act, and is itself influenced by preceding events that might cause a reasonable person to lose self control. 

oppression

noun
  • The exercise of authority or power in a burdensome, cruel, or unjust manner. 

  • The act of oppressing, or the state of being oppressed. 

  • A feeling of being oppressed. 

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