In April 2016, South Korea's population was estimated to be around 50.8 million by National Statistical Office, with continuing decline of working age population and total fertility rate. In a further indication of South Korea's dramatic decline in fertility, in 2020 the country recorded more deaths than births, resulting in a population decline for the first time since modern records began. In 2021, the fertility rate stood at just 0.81 children per woman. The country is noted for its population density, which was an estimated 505 per square kilometer in 2015, more than 10 times the global average. Aside from micro-states and city-states, South Korea is the world's third most densely-populated country. In practice the population density in much of South Korea is higher than the national one, as most of the country's land is uninhabitable due to being used for other purposes such as farming. Most South Koreans live in urban areas, because of rapid migration from the countryside during the country's quick economic expansion in the 1970s, 1980s and 1990s.