Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd1999 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         43        0.43        0.43
          3 |         23        0.23        0.66
          4 |        108        1.08        1.74
          5 |          4        0.04        1.78
          6 |      1,872       18.72       20.50
          7 |         73        0.73       21.23
          . |      7,877       78.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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