The trend shows that, the ratio of cost to population was declining, and of cost to economy firstly went up and then fall, this change comply with the law of economics.

• 从变化趋势看，计划生育成本-人口数量效益波动下降，成本-人口经济效益则由稳步上升转为逐年下降，这一变化符合经济学一般规律。