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Data Set #031

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About the Data

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".  Population distributions of Mexico (rapid growth) and Germany (negative growth) can be found in QELP datasets #032 and #033 , respectively.

     The US population pyramid is nearly symmetric about the vertical axis reflecting the fact that all age groups contain roughly equal numbers of males and females.  There are slightly more males up until age group 20-25. The drop in the number of males as compared to females is quite substantial in age group 25-29 (why?), and then after the number of females exceeding the number of males slowly grows. There is a population "bulge" in the middle of the pyramid representing the so called baby boomers of ages 35 to 50, and another small bulge for ages between 10 and 20 years.  The small bulge represents mostly children of baby boomers and is an "echo" of the older and larger baby boom generation.  The number of people of working age (between 20 and 65) is about 162 million and the number older than 65 is 35 million; this is roughly a ratio of 4.5 workers to 1  retiree. Will the same ratio exist in 15 to 30 years when the baby boomers enter retirement age? What would the population pyramid look like if 4.5 workers were needed to support every retiree in the future?

    The number of individuals in one age group that move to the next age group is based upon each age group's survival rate.  For example, every five years a fraction of age group 15-19 will survive to graduate to the 20 to 24 year age group.  As a country ages, the population distribution and corresponding pyramid shape will generally change. For example, the population bulge in the middle of the US pyramid will (most likely) move upwards over time so that in 25  years the bulge will be present at the top of the pyramid.  Dynamic, time dependent population pyramids can be viewed at 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.

Source of the Data:  US Census  http://www.census.gov/

     
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United States Population, year 2000

Source: US Census Bureau

AGE

MALE

FEMALE

00-04

9639

9227

05-09

10122

9659

10-14

10196

9712

15-19

10237

9672

20-24

9502

9098

25-29

8926

8993

30-34

9721

9904

35-39

11105

11209

40-44

11231

11402

45-49

9780

10126

50-54

8399

8867

55-59

6398

6927

60-64

5046

5631

65-69

4334

5102

70-74

3876

4877

75-79

3103

4319

80-84

1866

3047

85-89

883

1821

90-94

319

861

95+

92

336

 

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