concomitance vs coöccurrence

concomitance

noun
  • occurrence or existence together or in connection with one another, coexistence 

  • A concomitant. 

  • The Roman Catholic doctrine of the existence of the entire body of Christ in the Eucharist, under each element, so that the body and blood are both received by communication in one kind only. 

coöccurrence

noun
  • The fact of a thing occurring simultaneously with something else; correlation. 

  • An instance of a thing occurring simultaneously with something else; coïncidence. 

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