Frequencies for first 10,000 rows of ifyes variable in namcs1994 dataset :

       if seen |
   before, for |
  diagnosis in |
     item 11a? |      Freq.     Percent        Cum.
---------------+-----------------------------------
Not applicable |      1,374       13.74       13.74
           Yes |      5,913       59.13       72.87
            No |      2,713       27.13      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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