Frequencies for first 10,000 rows of hincomer variable in namcs2007 dataset :

  median household income in |
               patient's zip |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                missing data |        645        6.45        6.45
  quartile 1 (below $32,793) |      1,937       19.37       25.82
quartile 2 ($32,794-$40,626) |      2,230       22.30       48.12
quartile 3 ($40,627-$52,387) |      2,281       22.81       70.93
quartile 4 ($52,388 or more) |      2,907       29.07      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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