Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd1996 dataset :

 controlled |
  substance |
   code for |
 medication |
         #1 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        200        2.00        2.00
          3 |         78        0.78        2.78
          4 |        186        1.86        4.64
          5 |         10        0.10        4.74
          6 |      5,343       53.43       58.17
          7 |        250        2.50       60.67
          . |      3,933       39.33      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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