The dollar declined abruptly in value against the yen in the second quarter of 1994, spurring the central banks of seventeen nations to coordinate a series of intervention efforts in the world's currency trading markets. In addition, the dollar's decline sparked discussions of the possible policy moves the United States and other nations might take to stem the fluctuations in the value of the dollar. Economic theory and empirical evidence indicate that the underlying movement of the exchange rate is tied to the long-term, macroeconomic movements of the economy, or to the combined movements of the economies of different countries, such as the United States and Japan. These macroeconomic factors account for at least half of the overall movement of exchange rates.