Preliminary numbers released by the U.S. Energy Information Administration indicate Wyoming mines produced about 9 percent less coal last year compared with 2011.

Nationwide, coal production dropped about 7 percent, to 1.02 billion tons. Industry officials say the decrease in production is due to sagging natural gas prices, a mild winter and stricter regulations on coal-burning power plants.

State financial analysts are warning that Wyoming needs to brace for flat revenues for years to come given the slumping national demand for coal and increasing natural gas production in other states.  The majority of Wyoming’s revenues come from taxes from coal and natural gas production.