Frequencies for first 10,000 rows of ume_vbac variable in natl2007 dataset :

    Vaginal |
      after |
  C-Section |
        RFP |
731=f_u_vba |
        c U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        160        1.60        1.60
          2 |      9,781       97.81       99.41
          9 |         59        0.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015