Tokyo--Jan. 24--Japan's trade surplus fell for the sixth straight month in December, declining 27.4% from a year earlier to 816.1 billion yen, the Ministry of Finance announced. The data was below private economists' expectations of an 848 billion yen surplus. Exports rose 8.2% on year while imports surged 20.9% because of a rise in crude oil. The trade surplus with the U.S. increased 16% on year to 689.6 billion yen.