Frequencies for first 10,000 rows of contsub4 variable in namcs2007 dataset :

    controlled status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         30        0.30        0.30
              schedule iii |         31        0.31        0.61
               schedule iv |        118        1.18        1.79
                schedule v |         16        0.16        1.95
                no control |      2,186       21.86       23.81
              undetermined |         53        0.53       24.34
                         . |      7,566       75.66      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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