Frequencies for first 10,000 rows of contsub2 variable in nhamcsed1999 dataset :

 controlled |
  substance |
   code for |
    drug #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        185        1.85        1.85
          3 |        163        1.63        3.48
          4 |        123        1.23        4.71
          5 |         15        0.15        4.86
          6 |      3,381       33.81       38.67
          7 |        155        1.55       40.22
          . |      5,978       59.78      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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