Frequencies for first 10,000 rows of rx1v1c3 variable in nhamcsed2006 dataset :

   for rx1, level 1 of multum |
             drug category #3 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
central nervous system agents |        126        1.26        1.26
                     hormones |          3        0.03        1.29
         miscellaneous agents |          1        0.01        1.30
           respiratory agents |         20        0.20        1.50
                            . |      9,850       98.50      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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