Frequencies for first 10,000 rows of sigprov variable in namcs2014 dataset :

 Sigmoidoscopy |
      provided |      Freq.     Percent        Cum.
---------------+-----------------------------------
         Blank |          2        0.02        0.02
Not applicable |      9,957       99.57       99.59
           Yes |         40        0.40       99.99
            No |          1        0.01      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 27 Mar 2017