The demographics of Thailand paint a statistical portrait of the national population. Demography includes such measures as population density and distribution, ethnicity, educational levels, public health metrics, fertility, economic status, religious affiliation, and other characteristics of the populace. Population The population of Thailand was estimated to be . Thailand's population is mostly rural. It is concentrated in the rice growing areas of the central, northeastern, and northern regions. Its urban population—principally in greater Bangkok—was 45.7 percent of the total population in 2010 according to National Economic and Social Development Board (NESDB). Accurate statistics are difficult to arrive at, as millions of Thai migrate from rural areas to cities, then return to their place of origin to help with seasonal field work. Officially they have rural residency, but spend most of the year in urban areas. Thailand's successful government-sponsored family planning program has resulted in a decline in population growth from 3.1 percent in 1960 to around 0.4 percent in 2015. The World Bank forecasts a contraction of the working-age population of about 10 percent between 2010 and 2040. In 1970, an average of 5.7 people lived in a Thai household. At the time of the 2010 census, the figure was down to 3.2. Even though Thailand has one of the better social security systems in Asia, the increasing population of elderly people is a challenge for the country. Life expectancy has risen, a reflection of Thailand's efforts to implement effective public health policies. The Thai AIDS epidemic had a major impact on the Thai population. Today, over 700,000 Thai are HIV or AIDS positive, approximately two percent of adult men and 1.5 percent of adult women. Every year, 30,000–50,000 Thai die from HIV or AIDS-related illnesses. Ninety percent of them are ages 20–24, the youngest range of the workforce. An aggressive public education campaign begun in the early-1990s reduced the number of new HIV infections from 150,000 to under 10,000 annually. The leading cause of death among the age cohort under 15 years of age: drowning. A study by the Child Safety Promotion and Injury Prevention Centre of Ramathibodi Hospital revealed that more than 1,400 youths under 15 years old died from drowning each year, or an average four deaths a day, becoming the top cause of deaths of children, even exceeding that of motorbike deaths. Thailand's Disease Control Department estimates that only 23 percent of Thai children under 15