The accession of ten new members on 1 May 2004 produced an increase of 74 million in the population of the European Union, which now counts 455 million inhabitants. The Europe of Six had 167 million inhabitants in 1957. Since that date, the population of the Community has thus increased by 288 million, as a result of successive enlargements (235 million) and of natural increase and migration (53 million). In recent years, the population growth of the Europe of Fifteen has come mainly from the balance of migration (roughly 1 million people a year), the natural increase being in the region of 0.4 million.
Among the new members, the eight countries of central Europe are characterized by a negative or at most very low population growth, the result of fertility that is lower than in the countries of the Europe of Fifteen and of mortality that is higher. Because of past trends, demographic ageing is slightly less marked in these countries than in the Fifteen.
The European Union of Twenty-Five represents around 7.5% of the world population (but 16% of the over-60s) and slightly more than 60% of the population of continental Europe. It exhibits a large differential in population growth relative to the United States (3.2 per 1,000 and 9.1 per 1,000, respectively).