Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd1999 dataset :

 controlled |
  substance |
   code for |
 medication |
          # |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        262        2.62        2.62
          3 |         82        0.82        3.44
          4 |        170        1.70        5.14
          5 |         12        0.12        5.26
          6 |      5,494       54.94       60.20
          7 |        232        2.32       62.52
          . |      3,748       37.48      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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