disimprovement vs pejoration

disimprovement

noun
  • attempt to make something better while ending up worse than before. 

  • Reduction from a better to a worse state. 

pejoration

noun
  • The act or process of becoming worse; worsening or degeneration. 

  • The process by which a word acquires a more negative meaning over time. 

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