Merriam Webster says 2004 was year of the blog
According to Merriam Webster 2004 was the year of the "blog". Here is the official meaning of the word "blog":
Blog noun [short for Weblog] (1999) : a Web site that contains an online personal journal with reflections, comments, and often hyperlinks provided by the writer.
Curiously the 10th most looked up word on MW was "defenestration" which means "a throwing of a person or thing out of a window"