Frequencies for first 10,000 rows of prescr1 variable in nhamcsed1999 dataset :

prescriptio |
   n status |
   code for |
    drug #1 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,481       44.81       44.81
          2 |      1,329       13.29       58.10
          3 |      1,063       10.63       68.73
          . |      3,127       31.27      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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