Frequencies for first 10,000 rows of su variable in nhamcsed1999 dataset :

   hospital |
   sampling |
  unit code |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      8,307       83.07       83.07
          2 |        848        8.48       91.55
          3 |        293        2.93       94.48
          4 |        260        2.60       97.08
          5 |        104        1.04       98.12
          6 |         84        0.84       98.96
          7 |         53        0.53       99.49
          8 |         51        0.51      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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