Frequencies for first 10,000 rows of usetobac variable in namcs2005 dataset :

    tobacco |
   use: not |
   current, |
    current |      Freq.     Percent        Cum.
------------+-----------------------------------
      Blank |        606        6.06        6.06
Not current |      6,505       65.05       71.11
    Current |        914        9.14       80.25
    Unknown |      1,975       19.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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