Chart format changed as of May 2004 Index reflects monthly factory unit shipments of major and comfort conditioning appliances as reported by AHAM, ARI, and GAMA, including APPLIANCE magazine estimates. Due to a change in reporting procedures at the Gas Appliance Manufacturers Association (GAMA), totals for cast-iron gas boilers, steel-gas boilers, cast-iron oil boilers, and steel-oil boilers will no longer be reported monthly, and will instead be reported on a quarterly basis.