Frequencies for first 10,000 rows of ono2 variable in nhamcsed2009 dataset :

    initial |
      vital |
  signs: on |
     oxygen |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      1,042       10.42       10.42
         -8 |      1,197       11.97       22.39
          1 |        391        3.91       26.30
          2 |      7,370       73.70      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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