If you spun a globe and stopped your finger 12 times on 12 random countries, they just might make more sense for a monetary union than the euro zone.
And here is your tweetable fact: A monetary union might make more sense for every nation starting with the letter "M" than it does for the euro zone.
If you find yourself wondering, as I did, how the 50 states within the U.S. would compare across this measure of dispersion, remember that the nice thing about the United States is that baked into the first word of our name is not only a monetary union (i.e.: we all use dollars) but also a fiscal union. If Mississippi has a bad year (or decade, or century), Washington doesn't debate whether we should force the state to raise taxes or cut spending to become more competitive. We just keep paying it Medicaid, which is basically a transfer from rich Americans to poor Americans, many of whom live in Mississippi.
Germany doesn't want to establish any sort of "Peripheraid" -- a permanent transfer program from the core to the periphery. And that's why you should be about as optimistic about the future of the current euro zone as you are about a monetary union for the all the countries in the world that start with the letter "M."