contributory vs unhelpful

contributory

noun
  • A person or thing that contributes. 

adj
  • Tending to contribute to a result 

  • Of, pertaining to, or involving a contribution 

unhelpful

adj
  • Not providing help or assistance; not helpful. 

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