Frequencies for first 10,000 rows of ab_aven6 variable in natlterr2014 dataset 

   Assisted |
Ventilation |
  > 6 hrs Y |
        Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,077       10.77       10.77
          N |      8,729       87.29       98.06
          U |         98        0.98       99.04
          Y |         96        0.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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