According to numbers released by the U.S. Mine Safety and Health Administration (MSHA) there were 20 fatalities in U.S. coal mines in 2013, the same number as in 2012.

West Virginia again led the nation's coal-producing states in mining deaths, with six coal miners killed on the job, according to preliminary federal statistics.

The state's total coal-mining deaths dropped from seven in 2012, but was still more than the four miners killed in Illinois or the two mining deaths each in Kentucky, Pennsylvania and Wyoming.

Utah, Ohio, Indiana and Alabama each recorded one coal-mining death, according to MSHA.

Last year's total of four coal deaths in Illinois was the most in that state since 1990, when four miners also died, according to MSHA data.

Nationwide, deaths in all sectors of mining increased, from 36 in 2012 to 42 in 2013. MSHA figures showed an increase in metal and nonmetal mining deaths from 16 to 22 during the same period.

Over the past dozen years, West Virginia has the most coal mining deaths of any state, with 129. Kentucky had the next-highest total, with 87. That time frame includes 2006, when 12 miners died in the Sago Mine disaster, and 2010, when 29 died in the Upper Big Branch Mine disaster.