Frequencies for first 10,000 rows of ab_aven1 variable in natlterr2007 dataset :

   Assisted |
Ventilation |
        RFP |
628=f_ab_ve |
       nt R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,163       61.63       61.63
          N |      3,727       37.27       98.90
          U |          1        0.01       98.91
          Y |        109        1.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015