Frequencies for first 10,000 rows of rx2v1c2 variable in nhamcsed2006 dataset :

   for rx2, level 1 of multum |
             drug category #2 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
              anti-infectives |         73        0.73        0.73
        cardiovascular agents |         73        0.73        1.46
central nervous system agents |        393        3.93        5.39
        coagulation modifiers |         53        0.53        5.92
                     hormones |          6        0.06        5.98
         miscellaneous agents |         51        0.51        6.49
         nutritional products |         11        0.11        6.60
           respiratory agents |        223        2.23        8.83
               topical agents |         27        0.27        9.10
     psychotherapeutic agents |         16        0.16        9.26
             metabolic agents |          1        0.01        9.27
                            . |      9,073       90.73      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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