translation.en: Go back further, and it's even more striking: Since the 60s, the middle class has shrunk by 20 percent, mainly because of the people tumbling out of it.
translation.zh: 再往前回顾一下会更 令人吃惊。 从六十年代起，中产阶级 缩小了百分之二十， 主要是人们达不到那个水平