PIP: Only 13 years ago, world population numbered 4 billion; on July 11, 1987, it reached 5 billion. By the turn of the century world population will have reached 6 billion, half of the world's population will be urban, and most of it will live in developing countries. Not only will there be a larger population, it will also be older. The world's population growth is slowing down, but it will take about 100 years before it stops. Developing countries are expected to grow 3 times faster than their developed country counterparts. Sub-Saharan Africa's growth rate of 3% is about double that of the rest of the world. Falling birth rates throughout Europe reflect a profound shift in norms and attitudes away from concerns for family and offspring to the rights and self-fulfillment of individuals. A tide of materialism, progressiveness, and post-materialism is moving people away from marriage and parenthood in Northern and Western Europe. Cohabitation is increasingly accepted as normal, and there are indications that as few as 50-60% of men and women in future generations will ever marry. Having a child is now more and more a deliberate choice made to achieve greater individual self-fulfillment. Many Europeans are convinced that below-replacement fertility and aging populations signal the end of national influence in world affairs and the collapse of social security funds. Large-scale immigration may become a major component of European population growth if recent restrictions are eased. The world's least developed countries are experiencing the slowest economic growth, with upper-middle income countries growing the fastest.