Percentage of claimants for Federal Black Lung Program benefits who received a determination of progressive massive fibrosis (PMF) during their claim process in the central Appalachian states of Kentucky, Virginia, and West Virginia compared with the rest of the United States, 1970–2016. Data restricted to those miners with between 5 and 60 years of coal mine employment. Data source: U.S. Department of Labor, Office of Workers’ Compensation Programs, Division of Coal Mine Workers’ Compensation.