Frequencies for first 10,000 rows of mddo variable in namcs2005 dataset :

                   md or do |      Freq.     Percent        Cum.
----------------------------+-----------------------------------
  M.D. - Doctor of Medicine |      7,794       77.94       77.94
D.O. - Doctor of Osteopathy |      2,206       22.06      100.00
----------------------------+-----------------------------------
                      Total |     10,000      100.00

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