Congenital anomalies are also known as birth defects, congenital disorders or congenital malformations. Congenital anomalies can be defined as structural or functional anomalies (e.g. metabolic disorders) that occur during intrauterine life and can be identified prenatally, at birth or later in life.
But unlike in 2012 when Wyoming was home to nine of the US' ten biggest coal mines, the Cowboy State had a bit more competition last year. North Dakota's Freedom mine has taken the spot of the US' tenth biggest coal producer, as Wyoming's Caballo slid off the top-ten chart. All production figures are in metric tonnes.
Average annual number of employed coal miners in the United States, 1890-2014. US employment in coal mining peaked in 1923, when there were 863,000 coal miners. Since then, mechanization has greatly improved productivity in coal mining, so that employment has declined at the same time coal production increased. The average number of coal mining employees declined to 65,400 in 2015.