The single most often quoted figure from the national accounts is probably the growth rate. This is the change in GDP (or GNP) at constant prices. Constant Prices means the change after any increases or decreases due to price changes have been removed. The volume (constant price) measures are calculated to base the previous year rather than to a fixed base. The annual volume changes are then chain linked to a reference year to produce indices and values of the main aggregates in “constant” prices.