Why would it matter who owns them or how many? That sort of calculation is not made with stock shares. The fact is those coins are still out there in the billions doing nothing. In the older population, they still owned in quantity. Practically every estate sale has some.
Maybe there is a preference for these coins to be melted rather than used as money as the government philosophy used to be ... and maybe still is ... "silver is more valuable for industry than for money". Or maybe, just maybe, silver is now more valuable as money than industry as it is just a small sliver of costs for industry.
A quick look at mintages, there were 5 billionish silver roosevelt dimes minted, a couple billion mercuries. Maybe only 1 billion survive after the melts. That would be 10 billion cash to boost economy in dimes alone, $100 cash drop per family. If quarters and halves are the same, another $200. Not for everyone, but those 1 dollar silver rings would now be worth $10 at the pawn shop.