Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd1992 dataset :

 Controlled |
  substance |
   code for |
 medication |
         #1 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         48        0.48        0.48
          3 |         69        0.69        1.17
          4 |         91        0.91        2.08
          5 |          8        0.08        2.16
          6 |      4,401       44.01       46.17
          7 |        397        3.97       50.14
          . |      4,986       49.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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