Call it America’s middle-class paradox. People who probably don’t earn enough to be middle class consider themselves to be part of this group.

Nearly half of Americans (49%) consider themselves middle class and only one-third of those that do are still satisfied with their financial situation, according to a survey of 2,000 people conducted by market-research group Mintel released Tuesday. What’s more, only one-quarter find their work personally fulfilling. “Americans want access to opportunities that improve the overall quality of their lives,” the study found. “This attitude might be related to income inequality, with people of average income levels feeling relatively unsatisfied with what they have compared to the top 1%.”

One problem: There is no universal definition of the middle class. The Pew Research Center often uses the middle wealth quintile, the middle 20% of Americans’ income and wealth. Other economists have said it’s defined as making 50% above or below the median annual income. Most Americans regard a college education as a critical component to becoming middle class. Some 71% of people with a college degree consider themselves middle class versus just 58% of people with a high school diploma or less, according to a 2012 survey by Gallup. And yet college graduates in 2017 are shouldering $1.3 trillion in student debt.

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Previous studies suggest those who identify as middle class as higher than 50%, but also indicates that the middle class is shrinking. Those who identify as middle class has fallen to 59% in 2010 from 62% in 1991, according to a separate report by the Pew Research Center, a nonprofit think tank in Washington, D.C. While that’s higher than the Mintel survey, it’s still a smaller percentage than 11 other European countries. “The American experience reflects a marked difference in how income is distributed in the U.S. compared with many countries in Western Europe,” that report said. “The U.S. has a relatively large upper income tier.”

“ ‘Income inequality, or the hollowing out of the middle class, has been seen in both the short-term and in the years going back before the financial crisis and the Great Recession.’ ” — Mark Hamrick, Washington, D.C. bureau chief for Bankrate.com

American economic growth has been a double-edged sword for many Americans. In 2010, households in the U.S. were more economically divided than households in the selected Western European countries analyzed by Pew. The U.S. is the only country in which fewer than 60% of adults were in the middle class when compared to those 11 other European countries. However, compared with those in many Western European countries, a greater share of Americans were either lower income (26%) or upper income (15%). The percentage of people who are middle class ranged from 64% in Spain to 80% in Denmark and Norway.

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“Income inequality, or the hollowing out of the middle class, has been seen in both the short-term and in the years going back before the financial crisis and the Great Recession,” says Mark Hamrick, Washington, D.C. bureau chief for the personal-finance site Bankrate.com. “The loss, or migration, of manufacturing jobs is part of the story. For example, as American consumers have gotten increased access to cheaper clothing and electronics, they have helped to spur employment of less expensive labor elsewhere. Consumers have benefited in the U.S. at the expense of many workers.”

But others say that many middle-class Americans are moving up in the world. “America’s middle class is disappearing,” says Mark Perry, professor of economics at University of Michigan-Flint, “but into higher income groups.” In inflation-adjusted dollars, the share of U.S. households making $100,000 or more has more than tripled between 1967 and 2017, from 8% to 26%, according to U.S. Census data, while the percentage of middle income ($35,000 to $100,000 a year) has fallen. However, lower income U.S. households ($35,000 or less per year) have only slightly fallen over the last four decades.

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The shift out of the middle class is a sign of economic progress, irrespective of changes in household incomes overall, wrote Rakesh Kochhar, an associate director of research at the Pew Research Center and author of the report. Some countries with shrinking middle classes saw a rise in household incomes, showing that many people are also moving into the upper-income tier in all countries with a shrinking middle class. The median incomes rose in Luxembourg, the U.S., Norway, the Netherlands, Denmark, France, Ireland and the U.K. between 1991 and 2010.

Compared with those in many Western European countries, a greater shares of Americans were upper income (15%). MarketWatch photo illustration/iStockphoto, Everett Collection

“ America’s middle class is disappearing, but into higher income groups. In inflation-adjusted dollars, the share of U.S. households making $100,000 or more has more than tripled between 1967 and 2017. ” — Mark Perry, professor of economics at University of Michigan-Flint

The middle-class share of the adult population fell in seven of the 11 Western European countries examined — Norway, Denmark, Luxembourg, plus Finland, Germany, Italy and Spain — mirroring the long-term shrinking of the middle class in the U.S. The bad news: Incomes barely budged or fell in those latter four countries. However, Pew reported that the middle class rose in the Netherlands and Spain, and soared in Ireland and the U.K. Ireland experienced the most rapid growth in income from 1991 to 2010 and the biggest expansion of the middle class.

“The U.S. represents a significant exception to this general relationship between national income and the middle-income share,” Kochhar noted. “The median income in the U.S. — roughly $53,000 per year — exceeded the median income in all countries but Luxembourg in 2010.” However, even as more middle-class Americans are moving up in the world, there is also a higher level of income inequality. “The gap between the earnings of households near the top of the income distribution and the earnings of those near the bottom is the widest in the U.S.,” he wrote.

Pew defines middle class adults as those with an annual disposable household income from two-thirds to double the national median disposable household income, after adjusting for household size. The income boundaries vary across countries, depending on a country’s own median disposable household income. Thus, the living standards of the middle class and of households in other income tiers also vary across countries. But there’s no universal definition. Americans regard a college education as a critical component to becoming middle class, previous surveys suggest.