A UC Berkeley study looked into who is creating most of the content online and they found that even though we have a plethora of easy publishing tools things have not changed that much: just 10 percent of us are creating and posting content. And moreover, the better educated you are, the more likely you are to post content.
Back in the days of the two-step communication theory, we were told that 10 percent of the people were opinion makers and the rest of us followed their lead. Seems that is still the case.