That's Germany's, I think the US is like 7700 tons.
In terms of personal ownership, lets say if they repeated what happened in the 30's (but this time, include non-bullion like set a limit on jewelry) lets say the -average- American owns 2oz of gold (adjusted for quality) and they set the limit at 1oz (ie, wedding/engagement/etc rings), and confiscate 1oz from everyone. That's 300million Troy, or about 10,000 tons.
Add in the bullion, and its 510 million Troy oz, or about 750 billion.