That is a nice chart.
How do you interpret it?
Presumably, in the past, the proportion of the tax burden paid by the top 5% was less than now.
This seems counter to what one would expect from the trends represented on this chart.
So there are other facts not represented by such a simple chart, such as the sheer number of persons in the top 5% and the amount of cash it takes to be in the top 5% have both changed also.
A greater number of persons paying top rates is just part of the good news, if there were fewer large fortunes there would have to be a greater burden on more smaller fortunes.
I believe the "gap" between the rich and the middle class is exaggerated, there are more of us in total so the number in the middle may have grown, but not as rapidly as the total has grown.
The people who are third, forth generation or more in the USA have reached zero population growth, almost all of our population increase is immigration, what financial demographic does that swell?