deterioration vs ongoing

deterioration

noun
  • The process of making or growing worse, or the state of having grown worse. 

ongoing

noun
  • Something that is going on; a happening. 

adj
  • Continuing, permanent, lasting. 

  • Presently or currently happening; being in progress. 

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