Frequencies for first 10,000 rows of ume_vbac variable in natlterr2006 dataset :

    Vaginal |
      after |
  C-Section |
        RFP |
731=f_u_vba |
        c U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         67        0.67        0.67
          2 |      4,748       47.48       48.15
          9 |      1,460       14.60       62.75
          . |      3,725       37.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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