Description:
About the population pyramid and data
Population pyramids are commonly used by demographers to illustrate age and sex structure of a country's population. Countries that are expected to grow rapidly typically have a large number of individuals in their reproductive years and the population pyramid is wider of "heavier" at the bottom. In contrast, populations that are expected to have slow, zero, or negative growth typically have more individuals beyond reproductive age, and their pyramids tend to be "top heavy".
Making predictions about a country's future population is aided by studying age cohorts (groups) such as those defined in the accompanying data set. Instead of considering a single growth or birth rate for the entire population, demographers estimate each cohort's birth and death rate to increase the predictive power of their models. Also taken into consideration is immigration and emigration from each cohort to other countries. Using dynamic cohort models, population pyramids can be computed predicting population structural changes over time. For an example of these pyramids visit the extraordinary website http://www.census.gov/ipc/www/idbpyr.html. This site is part of the much larger US Census International Data Base (IDB) website where additional country by country demographics can be found.
Germany's population structure is somewhat like that of the United States in that there is a "bulge" in the middle, reflecting the fact that the most numerous cohorts are in the age range of 30-55. In addition, the net number of migrants for each country is nearly the same, both numbering between 3 and 4 (per 1000 people). Also, both countries have advanced systems of education and health care, and both are highly industrialized with high employment of women. With these similarities, one might think that future population growth for these two countries would be similar. This is not the case. Models predict that the US population will continue to grow over the next 30 years at a rate of about 0.8% per year. In contrast, Germany's population growth rate, currently at 0.3% yearly, is predicted to drop. In about 20 years, despite sustained positive migration, the overall growth rate will become negative and the population of Germany will begin to decrease. (Note: If not for positive migration today, the growth rate would be negative as deaths exceed births by about 1.15 per 1000 people.)
