Frequencies for first 10,000 rows of su variable in nhamcsed1998 dataset :

   hospital |
   sampling |
  unit code |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      7,757       77.57       77.57
          2 |      1,156       11.56       89.13
          3 |        610        6.10       95.23
          4 |        270        2.70       97.93
          5 |        155        1.55       99.48
          6 |         52        0.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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