I was zooming in here to say exactly that.

Mind you, Silver is an industrial metal. It literally is used up when it is not minted and therfore stored in the people[s hands; and when it is not recycled from all the electronics and solar panels etc. that are sent to the dump. There is some gold used up in that way, for example in super-duper window-glass that reflects out sun-rays (I believe there is a building in Amsterdam that shines all golden), similar to mirror-glass that uses silver. The recent switch to digital photography has limited the drain that chemical film was on industrial silver.

So the 16:1 ratio was based on mines, i.e. supply, back when the Pound Sterling meant exactly that, with Gold sovereigns also factored into the money supply. But I believe that that ratio will become smaller as silver supply dwindles faster, and really it is only the poor man's precious metal in theory.