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

    Vaginal |
      after |
  C-Section |
 (ume_vbac) |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          7        0.07        0.07
          1 |      9,993       99.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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