When fertility is high and a country is young (median age below 20), there are huge numbers of children and the overall dependency ratio is high.
一个国家生育率高，表示这个国家很年轻（中位年龄在20岁以下），小孩数量庞大，依赖性比例相当高；
When fertility is high and a country is young (median age below 20), there are huge numbers of children and the overall dependency ratio is high.
一个国家生育率高，表示这个国家很年轻（中位年龄在20岁以下），小孩数量庞大，依赖性比例相当高；
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