commentary vs complication

commentary

noun
  • An oral relation of an event, especially broadcast by television or radio, as it occurs. 

  • A series of comments or annotations; especially, a book of explanations or expositions on the whole or a part of some other work. 

  • A brief account of transactions or events written hastily, as if for a memorandum. 

complication

noun
  • The act or process of complicating. 

  • A person who doesn't fit in with the main scheme of things; an interloper. 

  • The state of being complicated; intricate or confused relation of parts; complexity. 

  • A feature beyond basic time display in a timepiece. 

  • A disease or diseases, or adventitious circumstances or conditions, coexistent with and modifying a primary disease, but not necessarily connected with it. 

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