Population pyramid

A population pyramid is a graph. It has two back-to-back bars. These bars show the population in groups of ages, with woman in one side and man in the other side.

Expansive population pyramid of Angola for 2005 shows a young and rapidly growing population.

Constrictive population pyramid of China for 2005 shows an older population that won't grow so much.

The pyramids show the age distribution of the place, which can help in understanding and predicting the development of a country.

There are three types of population pyramids:

• Stationary pyramid shows a constant population, with equal birth rate and death rate
• Expansive pyramid shows a growing population
• Constrictive pyramid shows a shrinking population

In this type of graph, a wide base means a very high birth rate and a narrow base means a low birth rate.