The U.S. Department of Labor says the income gap between high- and low-income earners is expanding.

The department said nominal wages of workers in the top ten percent bracket jumped seven percent from mid-2009 to the first quarter of this year. But wages of workers in the bottom ten percent bracket increased a mere two-point-five percent during the same period.

Analysts said the gap has expanded further since the 2008 global financial crisis, attributing it to a rise in the number of U.S. companies that outsource production to countries with cheaper labor costs.