The population of Kenya in 2003 was estimated by the United Nations at 31,987,000, which placed it as number 34 in population among the 193 nations of the world. In that year approximately 3% of the population was over 65 years of age, with another 44% of the population under 15 years of age. There were 98 males for every 100 females in the country in 2003. According to the UN, the annual population growth rate for 2000–2005 is 1.45%, with the projected population for the year 2015 at 36,864,000. The population density in 2002 was 54 per sq km (139 per sq mi). Kenya's population has increased with remarkable rapidity in recent decades. According to UN estimates, the national total rose by 28% from 6,416,000 in 1950 to 8,189,000 in 1960; by 37% to 11,253,000 in 1970; by 46% to 16,466,000 in 1980; by 36% to 22,400,000 in 1987; and by 24% to an estimated 27,885,000 in 1995. About 75% of the population lives on only 10% of the land.
It was estimated by the Population Reference Bureau that 33% of the population lived in urban areas in 2001. The capital city, Nairobi, had a population of 2,205,000 in that year. Mombasa, the chief seaport, had an estimated 465,000. Other large cities and their estimated populations were Kisumu, 185,100; Nakuru, 163,000; Machakos, 116,100; Meru, 78,100; Eldoret, 104,900; and Nyeri, 88,600. According to the United Nations, the urban population growth rate for 2000–2005 was 4.1%.
The prevalence of AIDS/HIV has had a significant impact on the population of Kenya. The United Nations estimated that 15% of adults between the ages of 15–49 were living with HIV/AIDS in 2001. The AIDS epidemic causes higher death and infant mortality rates, and lowers life expectancy.