Frequencies for first 10,000 rows of monpre variable in natl1990 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        189        1.89        1.89
          1 |      1,356       13.56       15.45
          2 |      3,870       38.70       54.15
          3 |      2,060       20.60       74.75
          4 |      1,003       10.03       84.78
          5 |        614        6.14       90.92
          6 |        399        3.99       94.91
          7 |        225        2.25       97.16
          8 |        117        1.17       98.33
          9 |         37        0.37       98.70
         99 |        130        1.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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