Frequencies for first 10,000 rows of monpre variable in natl1996 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        127        1.27        1.27
          1 |      1,849       18.49       19.76
          2 |      4,354       43.54       63.30
          3 |      1,817       18.17       81.47
          4 |        773        7.73       89.20
          5 |        466        4.66       93.86
          6 |        268        2.68       96.54
          7 |        166        1.66       98.20
          8 |         78        0.78       98.98
          9 |         27        0.27       99.25
         99 |         75        0.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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