Frequencies for first 10,000 rows of rx4v1c4 variable in nhamcsed2006 dataset :

   for rx4, level 1 of multum |
             drug category #4 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
central nervous system agents |         15        0.15        0.15
                            . |      9,985       99.85      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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