The Cereals Price Index is compiled using the International Grains Council (IGC) Wheat Price Index of 10 quotations, 1 US maize quotation and 16 rice quotations. The rice quotations are combined into groups consisting of higher quality Indica, lower quality Indica, Japonica and Aromatic rice. Within each group, a simple average of the relative prices of appropriate quotations is calculated; then the average relative prices of each of the three varieties are combined by weighting them with their trade shares. Indices for wheat, coarse grains and rice are combined using export value weights of the base period 2002–2004.