Frequencies for first 10,000 rows of contsub2 variable in namcs1993 dataset :

 controlled |
  substance |
   code for |
 medication |
         #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         15        0.15        0.15
          3 |         93        0.93        1.08
          4 |        131        1.31        2.39
          5 |         47        0.47        2.86
          6 |      3,188       31.88       34.74
          7 |        154        1.54       36.28
          . |      6,372       63.72      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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