Frequencies for first 10,000 rows of rx6v1c3 variable in nhamcsed2006 dataset :

   for rx6, level 1 of multum |
             drug category #3 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
central nervous system agents |          5        0.05        0.05
         miscellaneous agents |          2        0.02        0.07
           respiratory agents |          2        0.02        0.09
                            . |      9,991       99.91      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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