Frequencies for first 10,000 rows of monpre variable in natl1991 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        158        1.58        1.58
          1 |      1,290       12.90       14.48
          2 |      4,103       41.03       55.51
          3 |      2,003       20.03       75.54
          4 |      1,036       10.36       85.90
          5 |        586        5.86       91.76
          6 |        365        3.65       95.41
          7 |        244        2.44       97.85
          8 |        124        1.24       99.09
          9 |         44        0.44       99.53
         99 |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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