- Population estimates - Population changes worldwide - Birth and death rates
Despite declining total fertility rates (TFR) in developed countries -- down from 5.0 in the 1960s to 2.0 in the 21st century -- populations continue to grow worldwide at the rate of 78 million per year (2010 data).
In addition to the fertility rate, the rate of population growth varies depending upon the age at which women start giving birth. A population where the women have children at a younger age will grow faster than other populations where women give birth later in life. Longevity is the life span of an individual, which has increased worldwide as well.
A population profile is a bar graph showing the number of people at each age for a given population. Population profiles are frequently used to analyze changes in populations over a specified period of time. A population profile also basically represents the age structure of a population. For example, the United States has a mixture of both young and old populations. Many third-world countries lean heavily towards younger populations, resulting in explosive population growth while several wealthier nations have older or graying populations.
In Italy and Japan, populations will be graying as the number of elderly people increases. Europe is also in the midst of an immigration wave, responding to international crises. Immigration does provide new workers and youth but also challenges existing culture, art and religion.
The United States has a fertility rate of 2.1 and has accepted immigrants every year. Expected population is 439 million by 2050. In developing countries, the fertility rate is 3.2, similar to the United States at the peak of the baby boom period.
Population momentum is the effect of current age structures on future populations.
CBR or crude birth rate is the number of births per 1,000 per year. CDR or crude death rate is the number of deaths per 1,000 per year. The term ‘crude' is used because there is no consideration of whether the individual is old or young, male or female.
You can determine the change in population using this formula: % increase or decrease in population: (CBR - CDR) ÷ 10