Frequencies for first 10,000 rows of contsub6 variable in nhamcsed1998 dataset :

 controlled |
  substance |
   code for |
    drug #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          7        0.07        0.07
          3 |          3        0.03        0.10
          4 |          9        0.09        0.19
          6 |        169        1.69        1.88
          7 |          6        0.06        1.94
          . |      9,806       98.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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