Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd1995 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         16        0.16        0.16
          3 |         33        0.33        0.49
          4 |         69        0.69        1.18
          5 |          2        0.02        1.20
          6 |      1,749       17.49       18.69
          7 |         79        0.79       19.48
          . |      8,052       80.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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