Frequencies for first 10,000 rows of monpre variable in natl2001 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        122        1.22        1.22
          1 |      1,969       19.69       20.91
          2 |      4,412       44.12       65.03
          3 |      1,798       17.98       83.01
          4 |        705        7.05       90.06
          5 |        463        4.63       94.69
          6 |        249        2.49       97.18
          7 |        156        1.56       98.74
          8 |         66        0.66       99.40
          9 |         24        0.24       99.64
         99 |         36        0.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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