With iShares MSCI EAFE Index Fund  (NYSE: EFA) in the doldrums with U.S. markets, you're probably tossing around the question: Why should I even bother with global investments? After all, aren't they supposed to hedge the losses you encounter when we slow down domestically?

Actually, there is a lengthy list of reasons. To start with, the U.S. might not contribute to global economics as much as you think it does.

According to the World Bank, the United States' economy currently represents 22% of the world's gross domestic product (GDP) -- less than the European Union. Similarly, the World Federation of Exchanges says that, as of October 2007, stocks listed on the Nasdaq and NYSE accounted for 32.7% of the total global stock market capitalization of $63 trillion.

This means that close to 80% of the world economy, and more than two-thirds of the world's listed-companies by capitalization, are based outside the U.S., and these figures are only bound to increase in percentage terms.                                                           

For example, two BRIC (Brazil, Russia, India, and China) powerhouses, China and India, illustrate this equation. The International Monetary Fund reports that the Chinese economy is expected to grow 10% in 2008, and India's growth is expected to clock in at 8% -- well above the anemic 1.5% rate expected from the U.S. And Goldman Sachs projects that by 2050, the BRIC nations will have four of the top six economies of the world -- the other two in the U.S. and Japan.

World equity markets 
Foreign markets are growing in importance -- late last year PetroChina (NYSE: PTR) briefly surpassed ExxonMobil (NYSE: XOM) as the world's most valuable company. And it's not only emerging market companies that are increasing in weight.

BHP Billiton (NYSE: BHP), which holds the title of world's largest mining company by revenue, is headquartered in Australia, and in terms of subscribers, U.K.-based Vodafone (NYSE: VOD) is the world's second-largest telecom operator.

Simply put, investors who limit themselves to domestic stocks are losing the global rat race ... and as we know, in China 2008 is the Year of the Rat.

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Fool contributor Will Frankenhoff enjoys writing for The Fool more than reading The Financial Times, rooting for the Jints, or taking a nap. He welcomes your feedback. He does not own shares in any of the companies mentioned above. The Fool has a disclosure policy.