disimprovement vs pejorativization

disimprovement

noun
  • Reduction from a better to a worse state. 

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

pejorativization

noun
  • The process by which a term gains a more negative connotation over time. 

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