Frequencies for first 10,000 rows of monpre variable in natlterr1997 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        114        1.14        1.14
          1 |      1,281       12.81       13.95
          2 |      3,933       39.33       53.28
          3 |      2,446       24.46       77.74
          4 |      1,128       11.28       89.02
          5 |        568        5.68       94.70
          6 |        286        2.86       97.56
          7 |        140        1.40       98.96
          8 |         69        0.69       99.65
          9 |         15        0.15       99.80
         99 |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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