Most recently the iShares Silver Trust (SLV), the world's largest silver ETF, has been reporting the increased silver inflows to its vaults:

Source: Simple Digressions and SLV

As the chart shows, since the beginning of 2017 there was a continuous outflow of silver from SLV (the red arrow). However, in the middle of April this trend reversed and since that time (with a short break in May) we have seen a rapid increase of silver holdings at SLV (the green arrow).

Interestingly, the metal is hoarded at relatively low prices.