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

       DRUG |
INVOLVEMENT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      1,888       18.88       18.88
          1 |        110        1.10       19.98
          8 |      6,584       65.84       85.82
          9 |      1,418       14.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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