How much do countries rely on international trade? A common measure is the openness index, which adds imports and exports in goods and services and divides this sum by GDP. The larger the ratio, the more the country is exposed to international trade. Looking at the map, it’s quite apparent that the largest economies are the least open by this definition. But this is quite natural: Because they are so large, much of their trade is internal. For small economies that cannot produce everything they need, more trade has to be external. The extreme case here is Hong Kong, with a ratio of 440%. Indeed, it doubles as a trading hub, with more than its GDP being reexported.
Note: As of this writing, the last year available for this indicator is 2010. It is taken from the Penn World Tables, which are updated every few years.
How this map was created: Go to GeoFRED and select region type “Nation.” Look for “openness” in the dropdown menu.
Suggested by Christian Zimmermann.