Frequencies for first 10,000 rows of hincomer variable in namcs2010 dataset :

  median household income in |
               patient's zip |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                missing data |        650        6.50        6.50
  quartile 1 (below $32,793) |      1,869       18.69       25.19
quartile 2 ($32,794-$40,626) |      2,100       21.00       46.19
quartile 3 ($40,627-$52,387) |      2,352       23.52       69.71
quartile 4 ($52,388 or more) |      3,029       30.29      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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