Frequencies for first 10,000 rows of refer variable in namcs2000 dataset :

    was pat |
referred by |
        oth |
  physician |
 for visit? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,130       11.30       11.30
          2 |      8,357       83.57       94.87
          3 |        356        3.56       98.43
          4 |        157        1.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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