betterment vs perversion

betterment

noun
  • An improvement. 

  • An improvement to a property that adds to its value. 

perversion

noun
  • The action of perverting someone or something; humiliation; debasement. 

  • The state of being perverted; depravity; vice. 

  • Distortion or corruption of the original course, meaning, or state of something. 

  • A sexual practice considered abnormal; sexual deviance. 

  • Tendril perversion. 

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