This variable is the amount of public assistance payments (AFDC or TANF) that a respondent
received in this month and year. The variable comes from the core file. I20AMT1-I20AMT4
in 1984; S20AMT in the 1990, 1991, 1992, and 1993 panels; T20AMT in the 1996, 2001,
2004, and 2008 panels.