The Mine Safety and Health Administration (MSHA) have reported that 21 coal miners died in various mine accidents across the country last year.

This fatality rate is the second lowest in more than a century of record keeping. The lowest number was recorded in 2009 when 18 miners were killed.

The highest fatality was in the state of Kentucky with eight coal-mining deaths, followed by West Virginia with six. Arizona, Colorado, New Mexico, Virginia and Wyoming each recorded one coal-mining fatality, while two coal miners died in Ohio. Larger coal-producing states including Alabama, Pennsylvania, Illinois and Utah, experienced zero mine fatalities in 2011, the MSHA reported.

MSHA chief Joe Main said: "The year that the Federal Mine Safety and Health Act of 1977 passed, 273 miners died and, since that time, fatality numbers have steadily declined."

The MSHA said that 16 miners also died at metal and non-metal mining operations, which makes a total 37 deaths across all mining sectors.

In 2010, the industry recorded 48 fatalities, which included 29 deaths in the Upper Big Branch Mine disaster.

Of these deaths, 12 occurred at surface coal mines, 11 at surface metal / non-metal mines, nine at underground coal mines and five at underground metal / non-metal mines, reports the Associate Press.

"In order to prevent mine deaths, operators must have in place effective safety and health management programs that are constantly evaluated, find-and-fix programs to identify and eliminate mine hazards, and training for all mining personnel," Main said.