Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd1997 dataset :

 controlled |
  substance |
   code for |
 medication |
          # |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        153        1.53        1.53
          3 |         53        0.53        2.06
          4 |        161        1.61        3.67
          5 |          9        0.09        3.76
          6 |      5,300       53.00       56.76
          7 |        204        2.04       58.80
          . |      4,120       41.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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