Economic development and mechanization of agriculture resulted in the fields being abandoned, and most of the population moving to find jobs in the main cities. The number of people working in the Tertiary and Quaternary sectors of the economy has increased significantly. Since 1999, the absolute number of births in Galicia has been increasing. In 2006, 21,392 births were registered in Galicia, 300 more than in 2005, according to the Instituto Galego de Estatística. Since 1981, the Galician life expectancy has increased by five years, thanks to a higher quality of life. Roman Catholicism is, by far, the largest religion in Galicia. In 2012, the proportion of Galicians that identify themselves as Roman Catholic was 82.2%. The principal cities are A Coruña, Ourense, Lugo, Pontevedra, Santiago de Compostela – the political capital and archiepiscopal seat – Vigo and Ferrol. The largest conurbations are:  Like many rural areas of Western Europe, Galicia's history has been defined by mass emigration. Significant internal migration took place from Galicia in the late 19th and early 20th centuries to the industrialized Spanish cities of Barcelona, Bilbao, Zaragoza and Madrid. Other Galicians emigrated to Latin America – Argentina, Uruguay, Venezuela, Mexico, Brazil and Cuba in particular. Fidel Castro was born in Cuba to a wealthy planter father who was an immigrant from Galicia; Castro's mother was of Galician descent. The two cities with the greatest number of people of Galician descent outside Galicia are Buenos Aires, Argentina, and nearby Montevideo, Uruguay. Immigration from Galicia was so significant in these areas that Argentines and Uruguayans now commonly refer to all Spaniards as "gallegos" (Galicians). During the Franco years, there was a new wave of emigration out of Galicia to other European countries, most notably to France, Germany, Switzerland, and the United Kingdom. Many of these immigrant or expatriate communities have their own groups or clubs, which they formed in the first decades of settling in a new place. The Galician diaspora is so widespread that websites such as Fillos de Galicia have been created in the 21st century to organize and form a network of ethnic Galicians throughout the world. After this, a third wave was a Spanish internal emigration to heavier industrialised areas of Spain, like the Basque Country or Catalunya.