Poorer countries tend to have a disproportionately younger population. China is relatively unique in that it's got a much older population skew, due to the one

Poorer countries tend to have a disproportionately younger population. China is relatively unique in that it's got a much older population skew, due to the one child policy, but it isn't a developed wealthy country. Not completely unique: Russia is in a similar demographic situation. But most poorer countries have a much smaller elderly population than China.