Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd2007 dataset :

       for rx6, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         36        0.36        0.36
              schedule iii |         17        0.17        0.53
               schedule iv |         48        0.48        1.01
                schedule v |          5        0.05        1.06
                no control |      1,359       13.59       14.65
              undetermined |         14        0.14       14.79
                         . |      8,521       85.21      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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