Frequencies for first 10,000 rows of refer variable in namcs1997 dataset :

    was pat |
referred by |
        oth |
  physician |
 for visit? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,621       16.21       16.21
          2 |      7,982       79.82       96.03
          3 |        264        2.64       98.67
          4 |        133        1.33      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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