Frequencies for first 10,000 rows of ume_vbac variable in linkpe2009psden dataset :

    Vaginal |
      after |
  C-Section |
        U;R |
  (f_u_vbac |
  rep flag) |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         49        0.49        0.49
          2 |      3,321       33.21       33.70
          9 |         52        0.52       34.22
          . |      6,578       65.78      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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