Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd2002 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         35        0.35        0.35
          3 |         10        0.10        0.45
          4 |         39        0.39        0.84
          5 |          1        0.01        0.85
          6 |      1,201       12.01       12.86
          7 |         35        0.35       13.21
          . |      8,679       86.79      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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