by design vs fortuitously

by design

adv
  • Intentionally, designed specifically for a given purpose. 

fortuitously

adv
  • In a fortuitous manner; in a manner of happening by chance; coincidentally; accidentally. 

  • In a fortuitous manner; in a manner of happening by a lucky chance; luckily; fortunately. 

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