Frequencies for first 10,000 rows of referfl variable in nhamcsopd1993 dataset :

        was |
  patient's |
   referral |
     status |
   imputed? |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,506       95.06       95.06
          1 |        494        4.94      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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