Frequencies for first 10,000 rows of refphys variable in nhamcsed1997 dataset :

returned to |
  referring |
  physician |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,684       86.84       86.84
          1 |      1,316       13.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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