人是社会发展最基本的要素。随着人类社会的不断推进，世界人口呈上升的趋势。尤其是近几十年来在发展中国家，由于社会、政治方面较为稳定，各国努力发展自身经济，使得居民的生活水平不断提高，生活条件日益改善，从而导致社会总人口持续增长。-Man is the most basic elements of social development. With the continuous progress of human society, the world' s population was an upward trend. Especially in developing countries in recent decades, more stable social, political, national efforts to develop its own economy, residents and rising living standards, living conditions are improving day by day, resulting in the total population of the community continued to grow.