The U.S. trade gap narrowed sharply in December, the biggest deficit contraction in nearly four years. The unexpected decline likely means last week’s reported contraction in GDP will be revised to a positive number. Petroleum imports fell to the lowest level in more than a decade. The deficit decreased nearly 21% to $38.54 billion from a revised $48.61 billion the month before, the Commerce Department said Friday morning. Chief Economist Robert Brusca of Fact & Opinion Economics discusses the report with the Wall Street Journal Online’s Jim Chesko.