Frequencies for first 10,000 rows of contsub6 variable in nhamcsed2007 dataset :

       for rx6, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         36        0.36        0.36
              schedule iii |         18        0.18        0.54
               schedule iv |         16        0.16        0.70
                no control |        380        3.80        4.50
              undetermined |         13        0.13        4.63
                         . |      9,537       95.37      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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