The chart is a blanket representation of what happened and not enough information as to why.
In the last 20 years, we have seen a massive decline in manufacturing (outsourced to low wage countries like China, India, Phillipines, Mexico, etc.) and a massive increase in immigrants (mostly illegal) flooding in taking lower wages. Also automation (robotics) has increase 100x fold in 20 years.
It's easy to try and put all the blame on the 1%, but that's disingenuous.