The U.S. national debt is now about 73 percent of gross domestic product, higher than at any time since World War II and twice the percentage it was at the end of 2007, according to the Congressional Budget Office, MarketWatch reported. If current laws stay in place, debt will decline "slightly" relative to GDP over the next few years, the agency said. But it warned that 25 years from now, future deficits will have pushed the debt to 100 percent of GDP.