Injury shall mean material injury to an established domestic industry, threat of material injury to a domestic industry or material retardation of the establishment of a domestic industry. A determination of injury should be based on the investigation on 1) the volume of dumped imports; 2) the price of dumped imports, i.e. its reduction and impact on a similar product in the export market; 3) the impact of dumped imports on the domestic industry; and 4) the capacity of production, exportation and inventory of dumped imports in the exporting country.