3. Kuwait

Population: 3.6 million
Percentage of millionaire households: 11.8%

Kuwait owns about 7 percent of world oil reserves, and oil exports account for about 95 percent of export revenue. The government announced in 2010 that it would spend $130 billion in the next five years to move the economy away from oil dependency and diversify its private sector. Kuwait has about 63,000 millionaire households, with the Alghanim and al Kharafi families being the country's richest.

Data from: Boston Consulting Group and Bloomberg Billionaires