Frequencies for first 10,000 rows of drug_det variable in person dataset :

       DRUG |
DETERMAINAT |
        ION |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         97        0.97        0.97
          2 |          8        0.08        1.05
          3 |         62        0.62        1.67
          7 |         77        0.77        2.44
          8 |      9,756       97.56      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016