We had gone -- from 2001 to 2009, there was a period in which the average middle-class family lost 5 percent of their income -- 5 percent of their wages -- during that period.
This surge has been accompanied by the collapse of the lifetime-employment systems in Japanese and South Korean firms, which used to ensure that a single (male) worker's income could support a middle-class family.
The sociologist Viviana Zelizer points out that middle-class households, instead of paying for things out of one big pool of family income, tend to set aside particular sums every month for particular purposes, often keeping it in separate bank accounts depending on its purpose.