Frequencies for first 10,000 rows of contsub7 variable in nhamcsed2007 dataset :

       for rx7, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         13        0.13        0.13
              schedule iii |          4        0.04        0.17
               schedule iv |          8        0.08        0.25
                no control |        245        2.45        2.70
              undetermined |          2        0.02        2.72
                         . |      9,728       97.28      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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