irksome vs irritating

irksome

adj
  • Marked by irritation or annoyance; disagreeable; troublesome by reason of long continuance or repetition 

irritating

adj
  • Causing irritation, annoyance or pain. 

  • Stimulating or exciting a response. 

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