Frequencies for first 10,000 rows of rx4v1c3 variable in nhamcsed2006 dataset :

   for rx4, level 1 of multum |
             drug category #3 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
central nervous system agents |         16        0.16        0.16
         miscellaneous agents |          3        0.03        0.19
           respiratory agents |          6        0.06        0.25
                            . |      9,975       99.75      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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