Frequencies for first 10,000 rows of mpcb variable in linkco1991us_num dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        794        7.94        7.94
          1 |      1,662       16.62       24.56
          2 |      2,944       29.44       54.00
          3 |      1,774       17.74       71.74
          4 |        919        9.19       80.93
          5 |        630        6.30       87.23
          6 |        387        3.87       91.10
          7 |        223        2.23       93.33
          8 |        106        1.06       94.39
          9 |         68        0.68       95.07
         99 |        493        4.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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