The city of Paris (also called the Commune or Department of Paris) had a population of 2,165,423 people within its administrative city limits as of January 1, 2019. It is surrounded by the Paris unité urbaine, or urban area, the most populous urban area in the European Union. In 2018 the unité urbaine had a population of 10,816,803 in . The Paris Region, or Île-de-France covers , and has its own regional council and president. It has a population of 12,213,447 as of January 2018, or 18.3 percent of the population of France. The metropolitan or functional area (aire d'attraction) of Paris covers and has 13,064,617 inhabitants (2018). The population of the city of Paris reached a historic high of 2.9 million in 1921 but then declined; between 1954 and 1999 it declined at every census, falling to 2,125,246 in 1999. After that it began to climb again, reaching 2,240,621 in 2012, but falling to 2,187,526 in 2017. The city's population loss reflected the experience of most other core cities in the developed world that have not expanded their boundaries. The principal factors in the process were a significant decline in household size, and a dramatic migration of residents to the suburbs between 1962 and 1975. Factors in the migration included deindustrialisation, high rent, the gentrification of many inner quarters, the transformation of living space into offices, and greater affluence among working families. The city's population loss was one of the most severe among international municipalities and the largest for any that had achieved more than 2,000,000 residents. Since then, an influx of younger residents and immigrants has contributed to the growth of the city. Density According to Eurostat, the EU statistical agency, in 2012 the Commune of Paris was the most densely populated city in the European Union, with 21,616 people per square kilometre within the city limits (the NUTS-3 statistical area), ahead of Inner London West, which had 10,374 persons per square kilometre. According to the same census, three departments bordering Paris, Hauts-de-Seine, Seine-Saint-Denis and Val-de-Marne, had population densities of over ten thousand persons per square kilometre, ranking among the ten most densely populated areas of the EU. Paris is one of the most densely populated cities in the world. Its density, excluding the outlying woodland parks of Boulogne and Vincennes, was in the 1999 official census, which could be compared only with some Asian megapolises and the