Frequencies for first 10,000 rows of su variable in nhamcsed1995 dataset :

   hospital |
   sampling |
  unit code |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      8,801       88.01       88.01
          2 |        819        8.19       96.20
          3 |        148        1.48       97.68
          4 |         69        0.69       98.37
          5 |         64        0.64       99.01
          6 |         20        0.20       99.21
          7 |         27        0.27       99.48
         12 |         52        0.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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