Frequencies for first 10,000 rows of prescr4 variable in namcs2007 dataset :

 prescription status |
                code |      Freq.     Percent        Cum.
---------------------+-----------------------------------
   prescription drug |      2,172       21.72       21.72
nonprescription drug |        190        1.90       23.62
        undetermined |         72        0.72       24.34
                   . |      7,566       75.66      100.00
---------------------+-----------------------------------
               Total |     10,000      100.00

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