Frequencies for first 10,000 rows of hincomer variable in namcs2011 dataset :

    Recoded median household |
income in patient's ZIP code |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                Missing data |        649        6.49        6.49
  Quartile 1 (Below $32,793) |      1,778       17.78       24.27
Quartile 2 ($32,794-$40,626) |      2,298       22.98       47.25
Quartile 3 ($40,627-$52,387) |      2,404       24.04       71.29
Quartile 4 ($52,388 or more) |      2,871       28.71      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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