BILLINGS (AP) — The Montana Coal Council has announced that coal production across the state fell during the coronavirus pandemic, wearing on an already declining market.

Montana mines produced 15.1 million tons of coal in the first seven months of the year, 21% down compared to the same time last year, the Billings Gazette reported.

The pandemic has lowered energy demand and increased the number of people working from home, so coal-fired power plants have burned less in the United States and in other countries, officials said.

"It's a mix. In a worldwide pandemic, we're seeing it across the board, lower energy use," Council Executive Director Molly Schwend said.

The mine industry group compares production levels to 2016, which was a significantly low-demand year when cheap natural gas prices challenged the coal industry, Schwend said, adding that it was the same time cheap coal prices in export markets idled shipments of Montana coal through terminals in British Columbia.

Coal production in 2016 was 32.4 million tons, a steep decline from the 44.5 million tons mined in 2015, officials said. Since, coal exports have increased to 38.5 million tons in 2018 before falling to 34.8 million last year.

Earlier this year, Spring Creek Mine owner Navajo Transitional Energy Company announced furloughs at its mines in Montana and Wyoming. Spring Creek Mine laid off 73 workers in April and hired some back in July.

Decker Mine, nearby Spring Creek Mine, announced last week that it was furloughing 73 workers after already furloughing and recalling 98 workers in May.

Navajo Transitional Energy Company also furloughed 93 workers in May at its Antelope mine in Wyoming and laid off 80 workers last month.