Frequencies for first 10,000 rows of prescr2 variable in namcs2007 dataset :

 prescription status |
                code |      Freq.     Percent        Cum.
---------------------+-----------------------------------
   prescription drug |      4,491       44.91       44.91
nonprescription drug |        519        5.19       50.10
        undetermined |        138        1.38       51.48
                   . |      4,852       48.52      100.00
---------------------+-----------------------------------
               Total |     10,000      100.00

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