Frequencies for first 10,000 rows of mpcb variable in natl2003 dataset :

      Month |
   Prenatal |
 Care Began |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         35        0.35        0.35
          1 |      2,131       21.31       21.66
          2 |      3,329       33.29       54.95
          3 |      2,077       20.77       75.72
          4 |        753        7.53       83.25
          5 |        402        4.02       87.27
          6 |        261        2.61       89.88
          7 |        208        2.08       91.96
          8 |        143        1.43       93.39
          9 |        107        1.07       94.46
         99 |        554        5.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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