There are many ways of measuring historical changes. Time periods can be based on changes in global climate and geological change or cultural and political change. Technological change can also be a measurement of historical change.
When we look back at the year 1989 it introduced a crucial change through mass media technology. The world-wide web became accessible in a way that computer internet technology had never previously been.
The two charts show the basic break and shift in mass media. Print media’s dominance is reduced as digital print expands in various forms.