Frequencies for first 10,000 rows of monpre variable in natl1992 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        133        1.33        1.33
          1 |      1,514       15.14       16.47
          2 |      4,197       41.97       58.44
          3 |      1,865       18.65       77.09
          4 |        923        9.23       86.32
          5 |        606        6.06       92.38
          6 |        341        3.41       95.79
          7 |        242        2.42       98.21
          8 |        111        1.11       99.32
          9 |         36        0.36       99.68
         99 |         32        0.32      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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