Frequencies for first 10,000 rows of monpre variable in natl1999 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        138        1.38        1.38
          1 |      1,976       19.76       21.14
          2 |      4,655       46.55       67.69
          3 |      1,652       16.52       84.21
          4 |        690        6.90       91.11
          5 |        392        3.92       95.03
          6 |        231        2.31       97.34
          7 |        145        1.45       98.79
          8 |         82        0.82       99.61
          9 |         22        0.22       99.83
         99 |         17        0.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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