Derivation
INCRET is a 6-digit numeric variable.
999998 = Unknown/missing.
999999 = NIU (not in universe).
Panama 2000: 9997+
U.S.A. 1990: State median of values over 30,000
U.S.A. 2000: State median of values over 52,000
U.S.A. 2005: State median of values over 41,000
U.S.A. 2010: 99.5th percentile within each state (Higher values are the state means of all cases above these cutoffs.)
Puerto Rico 1990: State median of values over 20,000
Puerto Rico 2000: Mean of values over 52,000
Puerto Rico 2005: Mean of values above the 99.5th percentile
Puerto Rico 2010: 47400+