Age structure.
Rapid growth: a growth rate of 2.6% in Afghanistan is reflected in a bottom-up age structure, dominated by young individuals. Slow growth: a growth rate of 0.9% in the US shows a bulge in middle-aged "baby-boomers" born in the 2 decades after the end of World War II. The slow growth is sustained by immigration. No growth: Italy shows few young individuals, leading to a projection of a population decrease in the future. Video: