Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd1999 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         34        0.34        0.34
          3 |         10        0.10        0.44
          4 |         57        0.57        1.01
          5 |          2        0.02        1.03
          6 |      1,087       10.87       11.90
          7 |         23        0.23       12.13
          . |      8,787       87.87      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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