Frequencies for first 10,000 rows of mddo variable in namcs2004 dataset :

  type of physician - md or |
                         do |      Freq.     Percent        Cum.
----------------------------+-----------------------------------
  M.D. - Doctor of Medicine |      9,319       93.19       93.19
D.O. - Doctor of Osteopathy |        681        6.81      100.00
----------------------------+-----------------------------------
                      Total |     10,000      100.00

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