The size of New Jersey's middle class has been getting smaller, and the state saw a big spike in the number of wealthy households, according to new U.S. Census data.

Since the height of the recession, households with incomes at $200,000 or more experienced a 12 percent jump; there was a 10 percent increase in the number of households with an income of at least $125,000.

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Meanwhile, there was a drop in percentage at every level of income in the $35K-$125K range.

James Hughes, dean of the Edward J. Bloustein School of Planning and Public Policy at Rutgers University, said the trend's main culprit is a problem with job creation. In the 80s, 90s and early 2000s, the state was creating a solid amount of middle-skilled, white-collar jobs. However, since the recession, that creation has slowed down significantly.

"It may be the aftershock of the Great Recession. It may be due to globalization where those types of jobs can be outsourced," Hughes said. "It's certainly due to information technology and vast increases in computational power, whereby information technology is substituting for people."

Hughes said a college degree almost guaranteed someone a well-paying job in the past, but that's certainly not the case anymore. The growing white-collar jobs demand high-level skills and education, resulting in better pay.

The exodus from, and the entrance to, New Jersey can also be playing a role in the trend. The state's high cost of living may be forcing middle income-earners out of the state, while those who come in are foreign-born individuals looking for a start at the bottom or those who are already well-established and can handle New Jersey's expensive lifestyle.