Numerous factors contribute to falling birthrates in South America. As the bulk of countries' rural populations move to the city, traditional social structures break down. Access to education and the labor market and the higher cost of rearing children in urban and industrial environments encourages having fewer children. Youth typically enter the labor market only after finishing their education, which usually takes at least 20 years. To varying extents, all countries in South America have experienced urbanization and economic modernization, which affects social structures. South America has an average of 35 people over 65 years old for every 100 people under 15. By contrast, Europe has some 170 elderly people for every 100 young people. But South America is catching up. Countries like Brazil, Chile and Uruguay have had birthrates below the replacement level — 2.1, the number of children per woman needed to maintain a stable level of population — for almost a decade, while Argentina is currently at the replacement level. Other countries, such as Colombia, Venezuela, Paraguay and Peru, are still above replacement level. This will have two major consequences. First, South America is projected to reach its population peak by mid-century, at which point its population will begin to decline. Second, there will be more elderly people than young people by the mid-2030s in Brazil, Chile and Uruguay, by the mid-2040s in Argentina and by 2050 in the rest of the region.