Data on the percentage of ash in coal. Ash increases the weight of coal, adds to the cost of handling, and can affect its burning characteristics. Ash content is measured as a percent by weight of coal on an "as received" or a "dry" (moisture-free, usually part of a laboratory analysis) basis. Data organized by electric power sector, i.e., electric utility, independent power producers, commercial and institutional, and coke plants. Quarterly and annual data available. Based on Form EIA-3 and Form EIA-923 data. Users of the EIA API are required to obtain an API Key via this registration form: http://www.eia.gov/beta/api/register.cfm