Sharp Increase in World Population

　According to the figures given in the bar charts. it took from the beginning of human life to the year 1830 for the population of the earth to reach one billion.
　　That represents a time span of at least two million years. Then the world population increased rapidly, adding up to two billion in 1930. The next billion was added by 1960, Inflatable Advertising person only thirty years. From then on the global population was on the rise, amounting to 4 billion in 1975,which is another billion people in only 15 years. There are at least two reasons, I think, for the sharp increase in world population. In the first place, the birth rate is continuously climbing in many countries, especially in developing countries. Generally speaking, people there hold the opinion that children don't cost much and when they get old enough to work they will bring in money and that when parents are old, they will take care of them. Secondly, the death rate in most developed countries declines steadily because people's standards of living are raised and health care improves.