Frequencies for first 10,000 rows of ifyes variable in namcs1995 dataset :

       if seen |
   before, for |
  diagnosis in |
     item 11a? |      Freq.     Percent        Cum.
---------------+-----------------------------------
Not applicable |      1,089       10.89       10.89
           Yes |      6,199       61.99       72.88
            No |      2,712       27.12      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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