Frequencies for first 10,000 rows of su variable in nhamcsed1996 dataset :

   hospital |
   sampling |
  unit code |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      8,517       85.17       85.17
          2 |        758        7.58       92.75
          3 |        304        3.04       95.79
          4 |         95        0.95       96.74
          5 |        104        1.04       97.78
          6 |         45        0.45       98.23
          7 |         14        0.14       98.37
          8 |         12        0.12       98.49
         15 |         32        0.32       98.81
         24 |         67        0.67       99.48
         38 |         52        0.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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