Frequencies for first 10,000 rows of monpre variable in natl1989 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        165        1.65        1.65
          1 |      1,467       14.67       16.32
          2 |      3,658       36.58       52.90
          3 |      1,959       19.59       72.49
          4 |      1,018       10.18       82.67
          5 |        632        6.32       88.99
          6 |        422        4.22       93.21
          7 |        293        2.93       96.14
          8 |        135        1.35       97.49
          9 |         54        0.54       98.03
         99 |        197        1.97      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016