Frequencies for first 10,000 rows of mddo variable in namcs2011 dataset :

                   MD or DO |      Freq.     Percent        Cum.
----------------------------+-----------------------------------
  M.D. - Doctor of Medicine |      7,715       77.15       77.15
D.O. - Doctor of Osteopathy |      2,285       22.85      100.00
----------------------------+-----------------------------------
                      Total |     10,000      100.00

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