A brief introduction to the national average life expectancy;
The average life expectancy of the national population refers to the average number of years that people born in the same period can expect to live if the current age-specific mortality rate remains unchanged. It is not an actual data, but an important indicator to measure the population health status of a specific country and region based on the life table, which has an important relationship with the birth rate and mortality rate.
On July 12, 2022, the Statistical Bulletin on Health Development in China in 20021year issued by the National Health and Wellness Committee showed that the average life expectancy of Chinese residents increased from 77.93 years in 2020 to 78.2 years in 20021year.
Life expectancy:
In short, the average life expectancy is to assume that a group of people, starting from the age of 0, will gradually shrink until the last person dies according to the current mortality rate of all ages. The average age of death of these people is life expectancy.
Theoretically speaking, the average life expectancy should examine the actual life process of the same group of people. In other words, how many people born this year will die this year and how many will die next year and the year after. Assuming that these people will all die by 100, then their average life expectancy is the average life expectancy. But this statistical method is unrealistic, because it takes a century to calculate the life expectancy of this group of people.
The average life expectancy in demography refers to the current life expectancy. What is "the present"? It is based on the current mortality forecast (such as this year). For example, this group of people born this year will be 1 year old next year. 1 year mortality rate is related to medical conditions next year, and the situation next year is unknown. Therefore, according to the death probability of people 1 year-old this year, the number of deaths of these people 1 year-old is counted. When they live to be 2 years old, according to the death probability of 2 years old this year, the number of deaths is counted. And so on, go on year after year until all these people die, and calculate their average age of death.
Life expectancy per capita reflects the current level of death. Although it is called life expectancy, it doesn't mean how old these people can really live. Because it is calculated according to the current mortality rate, the mortality rate is constantly changing. For example, the life expectancy of these people born now is 74 years. After many years, the medical level has improved, and they may live to 100 years old.