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

       DRUG |
DETERMAINAT |
        ION |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        130        1.30        1.30
          2 |         23        0.23        1.53
          3 |         34        0.34        1.87
          7 |         73        0.73        2.60
          8 |      9,740       97.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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