payment rate described in subparagraph (A). (3) Administration (A) Reporting The Secretary shall ensure that any purchaser of Federal coal shall annually submit to the Secretary a report containing such information as the Secretary determines to be necessary to carry out this subsection. (B) Audits To carry out this subsection, the Secretary may examine the records of any person engaged in the purchase, sale, transportation, or marketing of Federal coal. (4) Coal price index (A) In general The Secretary shall compile in a coal price index the assessment values of coal by type and quality of coal. (B) Publication Not less frequently than quarterly, the Secretary shall publish in the Federal Register and on a public website the coal price index, along with a methodological description, including— (i) the method of calculation