centralization vs symbiosis

centralization

noun
  • The act or process of centralizing, or the state of being centralized; the act or process of combining or reducing several parts into a whole 

symbiosis

noun
  • The occurrence of two different or opposing things in the same time and place. 

  • A close, prolonged association between two or more organisms of different species, regardless of benefit to the members. 

  • A close, prolonged association between two or more organisms of different species that normally benefits both members. An interspecies cooperation. 

  • The state of people of different types, races, cultures, communities, etc., living together. 

  • A relationship of mutual benefit, especially among different species. 

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