Last year I went to Asia for the first time. I remember sitting down to eat lunch at a small roadside restaurant in the countryside outside of Phnom Penh, Cambodia. The menu was completely indecipherable to me, written entirely in the native Khmer language, except for two words:

Coca. Cola.

Many travelers have similar experiences, sitting more than 9,000 miles away from Coca-Cola (NYSE:KO) HQ in Atlanta and ordering a Coke. The drink, alongside Coca Cola's 50-plus other brands, seems ubiquitous -- and it is in many countries around the world. But the reality is that for Coke and PepsiCo (NASDAQ:PEP), growth will come from the emerging markets.

Same story, different day
Warren Buffett first invested in Coca-Cola in 1988. Over 25 years, the investment has turned into one of Buffett's greatest -- largely driven by Coke's success in markets outside the U.S. and Europe. 

That trend remains intact today. For the third quarter of this year, Coca-Cola reported a decline of 1% by volume in Europe and an increase in the U.S. of 1%.

Compare that with growth in China of 9% and India of 6%. 

The story is the same for PepsiCo, with beverage revenue growing in its Asia, Middle East, and Africa division by 6%, compared with a decline of 1.5% in the Americas. 

Logically, this should make sense. Both Coke and Pepsi are huge, widely known, and saturated in the U.S. and other Westernized markets. 

But, fortunately for growth, there are an estimated 7 billion people on Earth, and the majority of them don't live in the U.S. or Europe.

Using per-capita data to see the growth potential
According to Coca-Cola, the worldwide per-capita average consumption of 8-ounce Cokes in 2012 was 94. Mexico has the highest per capita of 745. The U.S. was fourth at 401.

In China, the world's largest country by population and the second largest economy, only 39 cokes were consumed per capita. India was even less at only 14. 

Indonesia has a population of more than 250 million people and a per-capita Coke consumption of only 15. Nearly 170 million people live in Nigeria, yet per-capita Coke consumption is just 26. 

These four countries alone -- China, India, Indonesia, and Nigeria -- represent more than 2.97 billion potential customers, all of whom live in a country with below average Coke consumption per capita. 

The potential for the company is staggering. As the world gets smaller, as emerging markets become developed, as Third World markets begin to emerge, Coke will be there.