Frequencies for first 10,000 rows of ono2 variable in nhamcsed2010 dataset :

    Initial |
      vital |
  signs: On |
     oxygen |      Freq.     Percent        Cum.
------------+-----------------------------------
      blank |        608        6.08        6.08
    unknown |      1,414       14.14       20.22
        yes |        519        5.19       25.41
         no |      7,459       74.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016