读数据要仔细，你们看看中医贴那PDF得page 9, minimum adjusted income，然后再读附注。估计这里双职工的都可以归到5％，除非你象比较高那样生了一打孩子，即便是律师＋医生家庭，一样归到bottom 80%
The minimum adjusted income is the lower income boundary for each quintile. Because incomes are adjusted by dividing income by the square root of household size, an adjusted income range implies different unadjusted income for different size households. To compute the unadjusted income range for a particular size household, the adjusted income must be multiplied by the square root of the household size: 1.414 for a two-person household, 1.732 for a three-person household; 2.0 for a four-person household, 2.236 for a five-person household. For example, in 2007, the highest quintile had adjusted income above $74,700. A two-person household would need
income above $105,600 to fall in that quintile, while a four-person household would need income in excess of $149,400.
