Frequencies for first 10,000 rows of none variable in namcs1993 dataset :

       does |
    patient |
have - none |
     of the |
      above |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,042       20.42       20.42
          1 |      7,958       79.58      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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