Frequencies for first 10,000 rows of monpre variable in natl1993 dataset :

     Detail |
   Month of |
  Pregnancy |
   Prenatal |
 Care Began |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         98        0.98        0.98
          1 |      1,615       16.15       17.13
          2 |      4,258       42.58       59.71
          3 |      1,960       19.60       79.31
          4 |        896        8.96       88.27
          5 |        529        5.29       93.56
          6 |        319        3.19       96.75
          7 |        174        1.74       98.49
          8 |         99        0.99       99.48
          9 |         32        0.32       99.80
         99 |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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