Frequencies for first 10,000 rows of su variable in nhamcsed1997 dataset :

   hospital |
   sampling |
  unit code |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      8,270       82.70       82.70
          2 |        831        8.31       91.01
          3 |        376        3.76       94.77
          4 |        186        1.86       96.63
          5 |        142        1.42       98.05
          6 |         55        0.55       98.60
          7 |         26        0.26       98.86
          8 |         24        0.24       99.10
         13 |         12        0.12       99.22
         14 |         35        0.35       99.57
         70 |         43        0.43      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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