Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd2009 dataset :

       for rx4, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         80        0.80        0.80
              schedule iii |         26        0.26        1.06
               schedule iv |         95        0.95        2.01
                schedule v |         16        0.16        2.17
                no control |      2,488       24.88       27.05
              undetermined |         35        0.35       27.40
        multiple schedules |          2        0.02       27.42
                         . |      7,258       72.58      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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