Frequencies for first 10,000 rows of smokcig variable in nhamcsopd1996 dataset :

       does |
    patient |
      smoke |
cigarettes? |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |      1,169       11.69       11.69
         No |      4,145       41.45       53.14
    Unknown |      4,686       46.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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