Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd2008 dataset :

       for rx6, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         37        0.37        0.37
              schedule iii |         20        0.20        0.57
               schedule iv |         44        0.44        1.01
                schedule v |          8        0.08        1.09
                no control |      1,478       14.78       15.87
              undetermined |         17        0.17       16.04
                         . |      8,396       83.96      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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