co-occurrence vs synchronicity

co-occurrence

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

  • An instance of a thing occurring simultaneously with something else; co-incidence. 

synchronicity

noun
  • Coincidences that seem to be meaningfully related; supposedly the result of "universal forces". 

  • The state of being synchronous or simultaneous. 

How often have the words co-occurrence and synchronicity occurred in a corpus of books? (source: Google Ngram Viewer )