A typical American born today can expect to live 78.8 years. While the U.S. life expectancy is better than in many parts of the world, it is three to five years shorter than the majority of developed nations. Further, despite spending far and away the most in the world on health care, the United States still trails many developed nations in other health measures as well.

In order to assess the overall state of a country’s health, 24/7 Wall St. reviewed a host of indicators reflecting the health of the population, access to care, and measures of the economy, which is often directly tied to health outcomes. The healthiest country this year was the small European nation of Luxembourg. South Sudan, meanwhile, is the least healthy country.

The least healthy countries in the world tend to perform poorly not just in a few health indicators, but in most measures of health. Infant mortality rates in these nations, for example, are all at least six times the U.S. rate. Maternal mortality rates are even worse. Tuberculosis is essentially a non-factor in most of the developed world — in the United States, there are just 3.1 new incidents of the disease each year for every 100,000 residents. In Lesotho, the rate is 852 per person for every 100,000 residents.

Click here to see the most healthy countries in the world.

Click here to see the least healthy countries in the world.

Combined, these negative health conditions result in extremely low life expectancies for the populations of the least healthy countries. While a typical American is expected to live 78.8 years, a person born in the Central African Republic is more likely than not to die before the age of 50. In nine of the 10 healthiest countries in the world, life expectancy is at least 80 years and as high as 83.3 years in Japan.

Countries that tend to perform well by some measures of health tend to rank well by most measures because of the link between socioeconomic factors and health. The healthiest countries tend to be relatively wealthy, have a robust economy and stable population growth, and provide access to basic amenities and care. The least healthy countries, on the other hand, tend to be the opposite: they are extremely poor, have a high population growth rate, and the population often lacks access to basic amenities — from clean water to health care.

In particular, it appears relative affluence in a country almost always results in a healthier population. Only one of the 10 healthiest nations, Japan, ranks outside of the 20 wealthiest nations based on GDP per capita. The two wealthiest countries in the world by this measure, Luxembourg and Qatar, are also the two healthiest countries. Income allows residents access to better health care options, to healthier eating and exercise facilities, and to higher education — which in turn allows them to make healthier choices.

Of course, greater spending itself does not guarantee better health outcomes. The United States, which ranks as the fourteenth-healthiest country in the world, spends $9,146 each year on health care, roughly $2,800 more than the next highest spender, Luxembourg.

The quality of a nation’s infrastructure and health care system is also closely related to its overall health. Doctors are far more available in the healthiest countries than in the least healthy ones, for example. The majority of the healthiest nations have among the highest rates of physicians per capita. Austria, for example, has 4.8 doctors for every 1,000 people, which is roughly double the U.S. concentration and which dwarfs the concentration in the least healthy countries. In Mozambique, for example, there are 0.04 physicians for every 1,000 residents.

Click here to read our methodology.

These are the most (and least) healthy countries in the world.