"The first decade of this century witnessed an historic reduction in global poverty and a near doubling of the number of people who could be considered middle income. But the emergence of a truly global middle class is still more promise than reality," said Rakesh Kochhar, associate director of research at Pew Research Center in a report on Wednesday.
In 2011, just over half (56 percent) of the world's population lived a "low-income existence," defined by Pew as a daily income between $2 and $10.
Only 13 percent were defined as "middle income," with an income of between $10 and $20 per day, up from 7 percent in 2001.
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Furthermore, the growth in this population was concentrated in China, South America and Eastern Europe, while the middle class barely expanded in India, Southeast Asia, Africa or Central America.
Plus, those "newly minted as middle class enjoy a standard of living that is modest by Western norms," said Kochhar. He noted that a daily income of $10-$20 a day translated into an annual income of $14,600 to $29,200 for a family of four—straddling the official poverty line in the U.S. in 2011.