OECD Data | Exchange RatesExchange rates are classified by the International Monetary Fund in three broad categories, reflecting the role of the authorities in the determination of the exchange rates and/or the multiplicity of exchange rates in a country: the market rate, in which the rate "floats" and is largely set by market forces; the official rate, in which the rate is "fixed" by a country's authorities; and arrangements falling between the two, in which the rate holds a stable value against another currency or a composite of currencies. This indicator is measured in terms of national currency per US dollar.