Frequencies for first 10,000 rows of smokcig variable in nhamcsed1995 dataset :

       does |
    patient |
      smoke |
cigarettes? |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |        560        5.60        5.60
         No |      3,196       31.96       37.56
    Unknown |      6,244       62.44      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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