Frequencies for first 10,000 rows of contsub4 variable in namcs2010 dataset :

    controlled status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         44        0.44        0.44
              schedule iii |         48        0.48        0.92
               schedule iv |         95        0.95        1.87
                schedule v |         11        0.11        1.98
                no control |      2,630       26.30       28.28
              undetermined |         31        0.31       28.59
        multiple schedules |          4        0.04       28.63
                         . |      7,137       71.37      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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