The nation's current account surplus in 1999 plunged 22.7 percent from a year earlier to 12.2 trillion yen, marking the first year-on-year decline in three years, the Finance Ministry said Monday. The surplus in merchandise trade -- exports minus imports -- fell 12.1 percent to 14.05 trillion yen, making it the biggest factor behind the current-account balance, the broadest gauge of the country's international economic standing. The current account measures the difference between a country's income from foreign sources and foreign obligations payable, excluding net capital investment. In December alone, the current-account surplus plummeted 39.9 percent to 871.5 billion yen, the 11th consecutive month of decline in a row, according to the report. With oil prices remaining at a high level and imports exceeding exports in volume, the shrinking of the current-account surplus will probably continue for the time being, a ministry official said. In all of 1999, a 6.3 percent drop in exports in merchandise, such as automobiles and iron and steel, was accompanied by a 3.5 percent decrease in imports, whose value was propped up by a rise in oil prices. The surplus in goods and services combined amounted to 7.87 trillion yen, down 17.4 percent. Crude oil prices averaged 12,111 yen per kiloliter, up 5.5 percent. The yen meanwhile averaged 113.94 to the dollar, against 131.02 a year earlier. A stronger yen can help reduce import prices and raise export prices. The deficit in services, such as communication and financial services, shrank 272.5 billion yen to 6.18 trillion yen. The income account, which covers income from Japanese investment in foreign securities and payments by foreign employers to workers in Japan, left a surplus of 5.71 trillion yen, down 1.69 trillion yen. This is partly attributed to smaller investment income because of the yen's appreciation.