Frequencies for first 10,000 rows of usetobac variable in namcs2008 dataset :

tobacco use |      Freq.     Percent        Cum.
------------+-----------------------------------
      blank |        523        5.23        5.23
    unknown |      2,345       23.45       28.68
not current |      6,302       63.02       91.70
    current |        830        8.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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