Frequencies for first 10,000 rows of ab_aven1 variable in natlterr2010 dataset :

   Assisted |
Ventilation |
        RFP |
628=f_ab_ve |
       nt R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      4,656       46.56       46.56
          N |      4,245       42.45       89.01
          U |        976        9.76       98.77
          Y |        123        1.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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