recession vs retrogradation

recession

noun
  • A period of reduced economic activity 

  • A procedure in which an extraocular muscle is detached from the globe of the eye and reattached posteriorly. 

  • The act or an instance of receding or withdrawing. 

  • A period of low temperatures that causes a reduction in species; ice age. 

  • The ceremonial filing out of clergy and/or choir at the end of a church service. 

  • The act of ceding something back. 

retrogradation

noun
  • Decline, degradation. 

  • A reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, largely responsible for bread becoming stale. 

  • Motion in a retrograde manner. 

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