Frequencies for first 10,000 rows of mddo variable in namcs2012 dataset :

  Type of doctor (MD or DO) |      Freq.     Percent        Cum.
----------------------------+-----------------------------------
  M.D. - Doctor of Medicine |      9,554       95.54       95.54
D.O. - Doctor of Osteopathy |        446        4.46      100.00
----------------------------+-----------------------------------
                      Total |     10,000      100.00

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