Frequencies for first 10,000 rows of contsub2 variable in nhamcsopd1998 dataset :

 controlled |
  substance |
   code for |
 medication |
         #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         51        0.51        0.51
          3 |         25        0.25        0.76
          4 |        178        1.78        2.54
          5 |          8        0.08        2.62
          6 |      3,205       32.05       34.67
          7 |        138        1.38       36.05
          . |      6,395       63.95      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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