To put this phenomenon in more precise terms: The Gini coefficient for income in the U.S., a number that quantifies a society's lack of economic equality, has been creeping up.

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One thing they all have in common is that their income inequality, as measured by the Gini coefficient, is well below that of the US. In fact, the Scandinavian and German-speaking countries that consistently score well on a variety of business and quality-of-life surveys have some of the lowest inequality scores among developed nations.

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Roughly speaking, a coefficient of zero would mean everyone was getting the same income.

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While some experts maintain that number still underestimates the nation's inequality, it would make the division of income as unequal as in the U.S., which had a Gini coefficient of 0.48 in 2011, according to the U.S. Census Bureau.

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