convenience vs difficulty

convenience

noun
  • The quality of being convenient. 

  • Any object that makes life more convenient; a helpful item. 

  • A convenient time. 

verb
  • To make convenient 

difficulty

noun
  • The state of being difficult, or hard to do. 

  • Physical danger from the environment, especially with risk of drowning 

  • An obstacle that hinders achievement of a goal. 

  • An objection. 

  • An awkward situation or quarrel. 

  • That which cannot be easily understood or believed. 

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