Lets just say that current public and corporate holdings are at 2% max in silver and the supply and demand at 29 with the help of the central banks.
My guess is 20 billion oz above ground at most.
Yes. There has been about 45 B oz silver produced since the dawn of mankind. About half of it is consumed or lost.
There remains less than 1 B oz "identifiable bullion inventories". This figure is down.
There is about 2 B oz in investment products and circulated coins.
There has to be about 5 B oz in jewelry and silverware since it is being produced at a constant rate.
An additional 10-15 B oz of silver exists but hard to say where and in what form.
The last silver spike in 1980 did not see a glut of unidentified silver coming to market. The identified stashes of circulated coins and silverware were quite depleted.
Silver has been in a positive demand since about 2006, meaning that investors are buying more than selling.
The total above ground silver grows only very slowly, about 0.5% a year, less than anything, even the population grows more.