In 1970s, gold experienced a bull market. At that time, the economies of the United States and Europe were low growth and high inflation, and the central bank adopted loose money by increasing debt. 1980 gold prices entered a bear market, the American economy stagnated, and the central bank stabilized the economy and controlled inflation. In the 1990s, the American economy recovered and changed from heavy industry production to new technology and service economy. In the late 1970s, the Organization of Petroleum Exporting Countries (OPEC) reduced its oil production, so the oil price rose, which affected the American and global economies and led to the economic recession in the late 1970s.