The scholarly community has no definitive answer as to what the ideal population for a country is. But economists estimate that if the fertility rate for women stays at about 2.1 --i.e. about two children per couple--after three generations (because life expectancy is extended) the birth date and death rate will balance off, and population will attain a steady zero growth rate.
一個國家最適合的人口是多少，學界並無定論，但經濟學者估計，婦女總生育率維持在二點一個水平不變，即平均生育兩個左右的子女，由於人的壽命不斷延長，在三代之後，會出現出生率與死亡率相抵，人口維持零成長的平衡狀態。