Why do you say indisputable. Not only is it but your premis is nothing but Democratic Party talking point lies.
Who Rules America: Wealth, Income, and Power
Table 4 shows clearly the changes are nominal and in fact minuscule over nearly 90 years. Also the table is based solely on percentage where as 1% in 1922 was 1.2 million and 1% today is distributed over 3.2 million.
Take your talking points for the DNC back to your beloved underground and do not state your opinion as fact.