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

       DRUG |
INVOLVEMENT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      1,077       10.77       10.77
          1 |         53        0.53       11.30
          8 |      7,703       77.03       88.33
          9 |      1,167       11.67      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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