Frequencies for first 10,000 rows of ab_aven6 variable in natlterr2009 dataset :

   Assisted |
Ventilation |
 >6 hrs RFP |
629=f_ab_ve |
      nt6 R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,449       24.49       24.49
          N |      7,374       73.74       98.23
          U |          2        0.02       98.25
          Y |        175        1.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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