Central America’s smallest and most densely populated country, El Salvador is also home to one of the region’s sharpest economic divides with the population largely split between the rich who made their wealth from sugar and coffee and poor farmers who rely on subsistence agriculture. According to a report from the U.S. Agency for International Development (USAID), El Salvador's per capita income is the fifth lowest in the Western Hemisphere when adjusted to reflect the cost of living. The healthcare system is in a state of disarray with strikes and inadequate supplies of basic drugs and medical equipment undermining treatment. Hospital budgets are used to pay salaries with little left over for other costs. The infant mortality rate is 31 per 1,000 (1997) and the death rate for children under 5 remains high at 81 per 1,000. El Salvador has the lowest life expectancy at birth in Central America. Complicating this picture is a fragile education system. According to the IDB, only 1 out of 3 poor Salvadorans graduates high school. The country has sustained significant ecological damage and pollution is a major concern. Only 59 percent of the population has access to safe drinking water. Recent studies have shown that the Lempa River, the country's central source of potable water, is contaminated with dangerously high levels of mercury and other heavy metals. The nation is plagued by the Maras, murderous criminal gangs that have overrun the country. El Salvador has the second-highest number of homicides in the world, registering 69.2 violent deaths per 100,000 inhabitants (NPR) and is one of the most dangerous nations not at war on the globe.