NEW YORK ( TheStreet) -- Working overseas and doing research on countries, I have always noticed striking differences and what explains them. Here, I look at four countries: China, Greece, Japan, and the U.S.I chose these four for specific reasons: The U.S. is the aging empire. In the '70s, it was thought Japan would be next, but China is now is expected to succeed the U.S. I selected Greece because it has been in the news recently, along with other reasons. Let's start by looking at a few common yardsticks for economic well-being.