Frequencies for first 10,000 rows of monpre variable in natl1998 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        131        1.31        1.31
          1 |      1,751       17.51       18.82
          2 |      4,657       46.57       65.39
          3 |      1,751       17.51       82.90
          4 |        715        7.15       90.05
          5 |        436        4.36       94.41
          6 |        227        2.27       96.68
          7 |        174        1.74       98.42
          8 |        100        1.00       99.42
          9 |         32        0.32       99.74
         99 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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