Frequencies for first 10,000 rows of ume_vbac variable in natlterr2009 dataset :

    Vaginal |
      after |
  C-Section |
        RFP |
731=f_u_vba |
        c U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         14        0.14        0.14
          2 |      1,081       10.81       10.95
          9 |      1,354       13.54       24.49
          . |      7,551       75.51      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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