The Tonnes column is the most recently published official figure for each country — not an estimate. The Previous column shows the prior month's reported holding. When these two numbers differ, the Change column shows the net purchase (green) or sale (red) in tonnes. A dash means the figure was unchanged.
The % of World bar shows each country's share of the ~36,582 tonne global official stock, scaled against the US (the largest holder at 8,133 t = 100% of the bar). The Reference column is critical: it tells you which month's data is actually shown. Countries like Germany and France report quarterly; China and others sometimes go months without updating, then post step-changes. Always check the reference date before drawing conclusions about recent activity.