Frequencies for first 10,000 rows of ume_vbac variable in natl2008 dataset :

    Vaginal |
      after |
  C-Section |
        RFP |
731=f_u_vba |
        c U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         54        0.54        0.54
          2 |      9,891       98.91       99.45
          9 |         55        0.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 May 2016