journey vs retrogression

journey

verb
  • To travel, to make a trip or voyage. 

noun
  • A group of giraffes. 

  • Any process or progression likened to a journey, especially one that involves difficulties or personal development. 

  • The weight of finished coins delivered at one time to the Master of the Mint. 

  • A set amount of travelling, seen as a single unit; a discrete trip, a voyage. 

retrogression

noun
  • A return to a less complex condition. 

  • A deterioration or decline to a previous state. 

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