Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd2007 dataset :

       for rx1, controlled |
     substance status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
schedule i (research only) |          1        0.01        0.01
               schedule ii |        251        2.51        2.52
              schedule iii |        175        1.75        4.27
               schedule iv |        200        2.00        6.27
                schedule v |         26        0.26        6.53
                no control |      6,012       60.12       66.65
              undetermined |        130        1.30       67.95
                         . |      3,205       32.05      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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