Frequencies for first 10,000 rows of contsub7 variable in nhamcsopd2007 dataset :

       for rx7, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
schedule i (research only) |          1        0.01        0.01
               schedule ii |         20        0.20        0.21
              schedule iii |         20        0.20        0.41
               schedule iv |         31        0.31        0.72
                schedule v |          5        0.05        0.77
                no control |      1,047       10.47       11.24
              undetermined |         18        0.18       11.42
                         . |      8,858       88.58      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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