A new study from the the University of Tübingen attempts to estimate the sizes of several developed nations' shadow economies. Not surprisingly, the biggest black markets on the list are in Greece, where the subterranean economy takes up 21.5 percent of the country's gross domestic product, and in Italy, where the figure is 19.8 percent. The smallest (relative to GDP) is in the United States, where the total is a mere 5.4 percent. You may be tempted to take that as a dispiriting signal that we've lost that insubordinate American spirit; I prefer to see it as a promising sign that our Leviathan doesn't drive as much peaceful trade underground.
If you can read German, you can check out the study here. Those of us who can't read German will have to make do with Forbes's write-up here. And if you just want to see a snappy infographic, Forbes and Statistica put together this handy chart: