than 50,000 inhabitants. The population is aging, although the process of immigration is countering the inversion of the population pyramid. Population change At the end of the 20th century, Andalusia was in the last phase of demographic transition. The death rate stagnated at around 8–9 per thousand, and the population came to be influenced mainly by birth and migration. In 1950, Andalusia had 20.04 percent of the national population of Spain. By 1981, this had declined to 17.09 percent. Although the Andalusian population was not declining in absolute terms, these relative losses were due to emigration great enough to nearly counterbalance having the highest birth rate in Spain. Since the 1980s, this process has reversed on all counts, and as of 2009, Andalusia has 17.82 percent of the Spanish population. The birth rate is sharply down, as is typical in developed economies, although it has lagged behind much of the rest of the world in this respect. Furthermore, prior emigrants have been returning to Andalusia. Beginning in the 1990s, others have been immigrating in large numbers as well, as Spain has become a country of net immigration. At the beginning of the 21st century, statistics show a slight increase in the birth rate, due in large part to the higher birth rate among immigrants. The result is that as of 2009, the trend toward rejuvenation of the population is among the strongest of any autonomous community of Spain, or of any comparable region in Europe. Structure At the beginning of the 21st century, the population structure of Andalusia shows a clear inversion of the population pyramid, with the largest cohorts falling between ages 25 and 50. Comparison of the population pyramid in 2008 to that in 1986 shows: A clear decrease in the population under the age of 25, due to a declining birth rate. An increase in the adult population, as the earlier, larger cohort born in the "baby boom" of the 1960s and 1970s reach adulthood. This effect has been exacerbated by immigration: the largest contingent of immigrants are young adults. A further increase in the adult population, and especially the older adult population, due to increased life expectancy. As far as composition by sex, two aspects stand out: the higher percentage of women in the elderly population, owing to women's longer life expectancy, and, on the other hand, the higher percentage of men of working age, due