The stationary or stagnant population pyramid with its bulb shape is the one that is the same size at its base and center, showing that there is no increase in any of its levels or in any of its appreciation ranges, that is, that the birth rate or mortality is similar or is maintained with the longevity of its inhabitants, showing the little evolution of the decline or drops in its birth rate in the last times of that nation, indicating that the progress instead of decaying is stable in this class of population, this is read as information towards the future of the little progress or demographic growth, of the stability and solidity of maintaining life, thus giving the typical model of a country without any development.
The population pyramid is a type of demographic history which by means of a graph shows constant or variable variables of certain characteristics of a given population, which can be displayed with horizontal bars where the length is distinguished by the quantity, the age, the sex of the people who inhabit it, where their representation is in each of the bars, thus calculating its decline or stability.
This type of pyramids shows the levels of low birth rates and low levels of mortality, emphasizing the adulthood of the beings that inhabit it and that the greater range of life that a person reaches is the stability that predominates in a complete nation, these data can be accurate or just give a margin of one percentage of demonstrated assertive information, which help to make comparisons with other nations, such as the assertiveness index to remain stable or that simply do not advance and the reason for this over others, thus being able to determine the kind of life that maintains this sector with longer life or the kind of stability that insecurity gives in order not to increase the new generations.
By being able to carry out such structured studies of a country or population, appropriate comparisons can be made at a global level to have as references what is happening in the present, as well as what has happened in the past, in order to define a possible present in the near future; taking into account that its purpose is to show the existence, weaknesses and strengths of both sexes, reflecting which type of population predominates more, among the young, the adult or the elderly, as man or woman, classifying what is known as the incoming and outgoing as an uncontrolled phenomenon indicating their influence on the population, such as migrations, wars or some kind of disease turned into an epidemic causing maximum deaths, in order to arrive at an apparently reliable record and its possible comparison with the rest of the world.
