Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd2001 dataset :

 controlled |
  substance |
   code for |
 medication |
         #1 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        180        1.80        1.80
          3 |         55        0.55        2.35
          4 |        113        1.13        3.48
          5 |         12        0.12        3.60
          6 |      5,213       52.13       55.73
          7 |        271        2.71       58.44
          . |      4,156       41.56      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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