The "law" of wealth concentration

[Carrol Cox]

I can't remember where I picked up the following spcculation or how
respectable the source was -- but sometime in the last 30 years I came
across an estimate that throughout the history of class society the
relative size of the ruling class under all conditions was about the
same -- around 2%. Anyone have any comment? Substantiation? Refutation?
Qualification or amendment?

Carrol