Frequencies for first 10,000 rows of hincomer variable in namcs2009 dataset :

  median household income in |
               patient's zip |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                missing data |        541        5.41        5.41
  quartile 1 (below $32,793) |      1,783       17.83       23.24
quartile 2 ($32,794-$40,626) |      2,218       22.18       45.42
quartile 3 ($40,627-$52,387) |      2,630       26.30       71.72
quartile 4 ($52,388 or more) |      2,828       28.28      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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