Frequencies for first 10,000 rows of refer variable in namcs1999 dataset :

    was pat |
referred by |
        oth |
  physician |
 for visit? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,301       23.01       23.01
          2 |      6,966       69.66       92.67
          3 |        551        5.51       98.18
          4 |        182        1.82      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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