Frequencies for first 10,000 rows of rx1v1c2 variable in nhamcsed2006 dataset :

   for rx1, level 1 of multum |
             drug category #2 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
              anti-infectives |        148        1.48        1.48
        cardiovascular agents |         82        0.82        2.30
central nervous system agents |        361        3.61        5.91
        coagulation modifiers |        125        1.25        7.16
      gastrointestinal agents |          1        0.01        7.17
                     hormones |         11        0.11        7.28
         miscellaneous agents |         79        0.79        8.07
         nutritional products |          6        0.06        8.13
           respiratory agents |        424        4.24       12.37
               topical agents |         31        0.31       12.68
     psychotherapeutic agents |         20        0.20       12.88
             metabolic agents |          3        0.03       12.91
                            . |      8,709       87.09      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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