"The son of the worker, on entering life, finds no field which he may till, no machine which he may tend, no mine in which he may dig, without accepting to leave a great part of what he will produce to a master. He must sell his labour for a scant and uncertain wage. His father and his grandfather have toiled to drain this field, to build this mill, to perfect this machine. They gave to the work the full measure of their strength, and what more could they give? But their heir comes into the world poorer than the lowest savage. If he obtains leave to till the fields, it is on condition of surrendering a quarter of the produce to his master, and another quarter to the government and the middlemen. And this tax, levied upon him by the State, the capitalist, the lord of the manor, and the middleman, is always increasing; it rarely leaves him the power to improve his system of culture. If he turns to industry, he is allowed to work--though not always even that --only on condition that he yield a half or two-thirds of the product to him whom the land recognizes as the owner of the machine.

We cry shame on the feudal baron who forbade the peasant to turn a clod of earth unless he surrendered to his lord a fourth of his crop. We call those the barbarous times. But if the forms have changed, the relations have remained the same, and the worker is forced, under the name of free contract, to accept feudal obligations. For, turn where he will, he can find no better conditions. Everything has become private property, and he must accept, or die of hunger." - Peter Kropotkin (The conquest of bread)

About 30%. And they've had more years to work, that's not a startling percentage.

As someone else said - mostly all rich people are old, but most old people are certainly not rich.