Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd1998 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         14        0.14        0.14
          3 |          9        0.09        0.23
          4 |         36        0.36        0.59
          5 |          3        0.03        0.62
          6 |      1,044       10.44       11.06
          7 |         37        0.37       11.43
          . |      8,857       88.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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