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

  return to |
  referring |
  physician |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,599       95.99       95.99
          1 |        401        4.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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