WASHINGTON (AP) — The United States cut its energy-related carbon dioxide pollution by 3.8 percent last year, the second biggest drop since 1990, the Department of Energy said Monday.

The only recent year with a bigger percentage drop was in 2009, when America was in a large recession. American cars and factories spewed 5.83 billion tons of carbon dioxide in 2012, down from 6.06 billion in 2011. It is the lowest level for U.S. emissions since 1994. Carbon dioxide is the chief man-made global warming gas.