translation.en: And they still have a child survival of only 70 to 80 percent, meaning that if you have six children born, there will be at least four who survive to the next generation.
translation.zh: 他们的儿童存活率还是 70%到80%。 也就是说，如果你有6个小孩， 最后只有4个能存活 变成下一代。