The countries slammed worst by plunging oil prices

This is not a great time to be an oil producer.

Extending a slide that began in June, crude prices have fallen by more than a third, and it's not clear how much lower they're heading. The drop has taken a multibillion-dollar bite out of the world economies that depend heavily on oil production.

It's also created a windfall for countries, companies and consumers that use all that oil.

The latest evidence came in Friday's trade data, which showed that U.S. oil imports—measured in dollars—fell in October to their lowest levels since November of 2009. The drop is being fueled by a boom in domestic energy production, falling demand due to improved efficiency and the recent plunge in oil prices.

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Each $10 drop in the global benchmark price amounts to about $330 billion—or about 0.4 percent of world GDP, according to Capital Economics economist Andrew Kenningham. So if oil prices hold their losses next year, he figures that about 1.2 percent of global GDP will shift from oil producers to consumers.

Foreign suppliers of U.S. oil have already been feeling the pinch from lower demand as a boom in domestic production has cut American imports. Since they peaked in August 2006, U.S. oil imports have slid by 40 percent as a production boom has boosted domestic supplies and sales of tens of millions of new, fuel-sipping cars have cut demand for gasoline.

Some U.S. suppliers have been hit harder than others. Despite its long dependence on oil from the Middle East, the U.S. imported nearly twice as much oil from non-OPEC sources in September than it did from cartel members. The bulk of those imports came from Canada—where a boom in oil production has helped create a glut of crude that is weighing on prices.

The crash in oil prices is costing those Canadian producers billions of loonies.

Before the price plunge, Canadian oil shipments had an annual customs value of nearly $85 billion, based on the first nine months of this year, according to U.S. Census Bureau trade data. With benchmark prices off by more than a third, Canada can expect to take a roughly $30 billion haircut on its oil sales next year.

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With a gross domestic product of roughly $1.8 trillion, the lost oil revenue comes to less than 2 percent of overall output. And the hit from falling oil revenue is expected to be offset by continued growth in other sectors, including strong consumer spending and non-energy exports. Canada's GDP grew by 2.8 percent in the third quarter after a 3.6 percent uptick in the prior three months.

"With momentum in other sectors, Canada's economy appears well-positioned to weather the storm (of lower oil prices)," according to Randall Bartlett, economist at TD Economics.

But other U.S. suppliers may not fare as well.

As the world's largest oil exporter, Saudi Arabia will take the biggest hit to revenues. If oil prices next year remain at levels a third below this year's peak, the lower price for U.S. exports alone will amount to about 2.5 percent of Saudi Arabian GDP.

Much depends on how long—and how low—oil prices pull back. Saudi Arabia has stashed away roughly $750 billion in foreign reserves, according to the Economist Intelligence Unit. Saudi Arabia's OPEC neighbors Kuwait and the UAE have about $100 billion in reserves between them, and much more held in their sovereign wealth funds, according to the EIU.

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But those governments also rely heavily on oil proceeds to fund government subsidies and infrastructure investment at levels much higher than the cash generated by crude at $70 a barrel. So a protracted era of lower prices would take a big toll.

Other oil producers have much thinner financial reserves to soften the blow. Russia and Venezuela have already burned through reserves to defend their currency, but the oil price plunge has hit both currencies hard. The Russian ruble is down by a third this year, and the Venezuelan bolivar is off by nearly two-thirds. That will make imported goods in those countries more expensive, fueling inflation and cutting demand and spending.

The GDP hits to oil producers, of course, will be offset by the windfall for oil consumers—both in the United States and other big importers like China, India and Japan.

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Not all of that windfall will fall directly to the GDP bottom line of oil-consuming countries, according to Kenningham, because some of it will be used to boost savings.

"(But) the propensity to consume is higher in countries which are net oil importers," he added. "Consumers will spend at least half the money they gain from the fall in oil prices."