In today's world, most companies span several regions and sell across the world. As Foolish colleague Morgan Housel notes, 10 years ago, less than a third of S&P 500 revenue growth came from abroad. Today, that area makes up half of the S&P 500's growth.

And that number is growing. The truth is, investors regularly underestimate how much demand comes from abroad. More importantly, for large, multinational corporations that have already established a presence in their home markets, much of their future growth comes from abroad.

With that in mind, today we're looking at Whole Foods (Nasdaq: WFM). We'll examine not only where its sales and earnings come from, but how its sales abroad have changed over time.

Where Whole Foods' sales were four years ago
Four years ago, Whole Foods was still in the early stages of its international push and produced 97% of its sales within the United States.

Source: S&P Capital IQ.

Where Whole Foods' sales are today
And today... The picture looks pretty much exactly the same.

Source: S&P Capital IQ.

So, why's Whole Foods not seeing international sales skyrocket like many of its peers in the S&P 500? For one, its international footprint still remains relatively limited. The company first expanded into the United Kingdom in 2004 when it purchased Fresh & Wild's seven locations. From that initial purchase the amount of stores in the United Kingdom has actually gone down to a total of just five today. In addition, Whole Foods also has seven locations in Canada. Compare that to the company's 299 stores in the United States.

In the end, grocery stores haven't been a type of American business that's translated well overseas. While Wal-Mart (NYSE: WMT) is the poster child of being able to aggressively expand a retail brand overseas, it has more going on other than groceries. Most pure-play grocery companies stick to the United States and Canada. Safeway (NYSE: SWY) receives an impressive 15% of its sales from Canada, but the remainder of sales all come from the United States. SUPERVALU (NYSE: SVU) and Kroger (NYSE: KR) report 100% of sales from within the states.

That's not to say Whole Foods' stateside potential is over. The company envisions building up to 1,000 stores in the United States. That would be more than triple the amount of American stores it operates today. Likewise, Canada could see a massive boom off its current footprint of seven stores. However, with Whole Foods appearing unable to find store growth even in the U.S.-like United Kingdom market, I wouldn't count on the same trend of international growth boosting the returns of U.S. multinationals if you're a Whole Foods investor.

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