Frequencies for first 10,000 rows of retref variable in nhamcsed2003 dataset :

  return to |
  referring |
  physician |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      8,696       86.96       86.96
        yes |      1,304       13.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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