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

  physician |
       seen |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        280        2.80        2.80
          1 |      9,720       97.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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