Frequencies for first 10,000 rows of monpre variable in natl1997 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         88        0.88        0.88
          1 |      1,882       18.82       19.70
          2 |      4,562       45.62       65.32
          3 |      1,708       17.08       82.40
          4 |        760        7.60       90.00
          5 |        415        4.15       94.15
          6 |        239        2.39       96.54
          7 |        159        1.59       98.13
          8 |         98        0.98       99.11
          9 |         39        0.39       99.50
         99 |         50        0.50      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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