Instead of answering this question, I'm going to tell you why it's a stupid one. There is no such thing as a universal intelligence that exists across all societies.
Many people think of IQ (which stands for "intelligence quotient") as the best way to measure a person's intelligence. The IQ was originally created in France, and was later modified in Germany and the United States. Since these are all developed countries, the IQ only measures forms of intelligence that are valued in developed countries. Specifically, it measures concentration, memory, verbal skills, and mathematical aptitude. Indeed, the most successful people in the U.S. are those who concentrate in school, memorize information, and score well on their SATs. These are the people who get into the best colleges and eventually get the best jobs. We therefore come to see them as intelligent.
But how useful are American forms of "intelligence" in starving nations like Somalia or Bangladesh? Having a large vocabulary or being good at math won't get you hired if there are no jobs to compete for in the first place. The people who are intelligent in those countries are the ones who simply know how to survive. That presumably requires a set of skills that aren't measured by the westernized IQ testsuch as: resilience, instinctual grit, physical toughness, etc. If you placed a Harvard graduate in the middle of the Sahara with no food or water, he wouldn't be "intelligent" enough to survive. At the same time, the savviest people in the undeveloped world might not even know how to read, and does, wouldn't be considered "intelligent" by Western standards.
So, which country contains the most intelligent people in the world? That depends on where you ask the question, because the "intelligent" people in Haiti have nothing in common with the "intelligent" people on Long Island.