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

   percent poverty in patient's zip |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
                       missing data |        647        6.47        6.47
quartile 1 (less than 5.00 percent) |      2,578       25.78       32.25
     quartile 2 (5.00-9.99 percent) |      3,048       30.48       62.73
   quartile 3 (10.00-19.99 percent) |      2,607       26.07       88.80
 quartile 4 (20.00 percent or more) |      1,120       11.20      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

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