Frequencies for first 10,000 rows of hincomer variable in nhamcsopd2006 dataset :

  median household income in |
          patient's zip code |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
  Quartile 1 (Below $32,793) |      3,009       30.09       30.09
Quartile 2 ($32,794-$40,626) |      2,470       24.70       54.79
Quartile 3 ($40,627-$52,387) |      2,009       20.09       74.88
Quartile 4 ($52,388 or more) |      1,943       19.43       94.31
                Missing data |        569        5.69      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016