Frequencies for first 10,000 rows of contsub6 variable in namcs2007 dataset :

    controlled status code |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
               schedule ii |         23        0.23        0.23
              schedule iii |         15        0.15        0.38
               schedule iv |         58        0.58        0.96
                schedule v |          7        0.07        1.03
                no control |      1,167       11.67       12.70
              undetermined |         18        0.18       12.88
                         . |      8,712       87.12      100.00
---------------------------+-----------------------------------
                     Total |     10,000      100.00

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