Wealth tax: 0%. Some states and municipalities in the US have a property tax but that functions in essentially the opposite way, since it hits people the most who have a large amount of property relative to their income (farmers and retirees), making it a regressive tax. There is no federal property tax.
The closest thing to a redistributive wealth tax is the estate tax, removed all together in 2001 and brought back in a lessor form in 2011. It's primarily politics which keeps us from having a proper wealth tax (though there's some question about implementation and catching tax dodgers), so we're stuck with an income tax instead. The trouble is that higher incomes are good for the economy, ideally we should be encouraging that sort of thing and not taxing it, while sitting on wealth is bad for the economy. But, like gas taxes, Americans can't seem to stomach doing things the sensible way because... I don't know, communism or something. Maybe too many people yelling "socialist!" So we're stuck with income taxes and excise taxes and sin taxes and yadda yadda.