synchronicity vs synchronism

synchronicity

noun
  • The state of being synchronous or simultaneous. 

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

synchronism

noun
  • The state of being synchronous. 

  • The tabular arrangement of contemporary events etc. in history. 

  • A temporal relationship between events. 

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