Frequencies for first 10,000 rows of ab_seiz variable in natl2014 dataset :

 Seizures Y |
        Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,727       97.27       97.27
          U |        269        2.69       99.96
          Y |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016