Frequencies for first 10,000 rows of ono2 variable in nhamcsed2013 dataset :

    Initial |
      vital |
  signs: On |
  oxygen on |
    arrival |      Freq.     Percent        Cum.
------------+-----------------------------------
      Blank |        272        2.72        2.72
    Unknown |      1,097       10.97       13.69
        Yes |        342        3.42       17.11
         No |      8,289       82.89      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016