disaster vs unpleasant experience

disaster

noun
  • An unexpected natural or man-made catastrophe of substantial extent causing significant physical damage or destruction, loss of life or sometimes permanent change to the natural environment. 

  • An unforeseen event causing great loss, upset or unpleasantness of whatever kind. 

unpleasant experience

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