Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd2001 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         41        0.41        0.41
          3 |         24        0.24        0.65
          4 |         60        0.60        1.25
          5 |          1        0.01        1.26
          6 |      1,967       19.67       20.93
          7 |        129        1.29       22.22
          . |      7,778       77.78      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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