A new study shows almost half of Americans with college degrees are in jobs for which they are overqualified.

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One of the study's authors says this is the new normal, fifteen percent of all cab drivers and one in four retail sales clerks have a Bachelor's degree.

The study, released by the non-profit Center for College Affordability and Productivity, says the trend is likely to continue for newly minted college graduates over the next decade.

"It is almost the new normal," says lead author Richard Vedder, an Ohio University economist and founder of the center, based in Washington.

Economic Analyst Patrick O'Keefe of Cohn-Reznick in Roseland says there are four-million fewer jobs in the U-S right now than there were in 2007. But he says the work-age population grew by more than 11-million.

O'Keefe says,"Most of that growth obviously occurs at the entry level, people coming out of school into the labor market."

The number of Americans whose highest academic degree was a bachelor's grew 25% to 41 million from 2002 to 2012, statistics released last week from the U.S. Census Bureau show.

The number with associate's degrees increased 31%, while the number of Americans for whom the highest level of education attainment was a master's or doctorate degree grew fastest of all - 45% and 43%, respectively.

The Census shows that in 2010, 5 percent of janitors had a Bachelor's degree, according to the study.