Frequencies for first 10,000 rows of rx1v2c3 variable in nhamcsopd2006 dataset :

        for rx1, level 2 of multum drug |
                            category #3 |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
CNS: Antiemetic/antivertigo agents: 5HT |         19        0.19        0.19
                 Hormones: sex hormones |         74        0.74        0.93
Miscellaneous agents: genitourinary tra |          1        0.01        0.94
    Respiratory agents: bronchodilators |          7        0.07        1.01
   Miscellaneous agents: antipsoriatics |          6        0.06        1.07
                                      . |      9,893       98.93      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

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