The Republic of Congo is an oil-rich middle income country which has a young and mostly urban population, with more than half of its 4.2 million inhabitants under the age of 20 and 62 percent of the population living in cities. According to the 2013 UNDP Human Development Report, the Republic of Congo is classified as a middle-income country and ranks 142 out of 186 countries on the Human Development Index. Income is unevenly distributed, however, and more than half of the population is living below the poverty line. The mortality rate for children under the age of five is 99 deaths per 1,000 live births, and the prevalence of stunting stands at 30 percent.