Frequencies for first 10,000 rows of smokcig variable in namcs1996 dataset :

       does |
    patient |
      smoke |
cigarettes? |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |      1,067       10.67       10.67
         No |      6,137       61.37       72.04
    Unknown |      2,796       27.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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