Frequencies for first 10,000 rows of mpcb variable in natl2004 dataset :

      Month |
   Prenatal |
 Care Began |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         36        0.36        0.36
          1 |      2,201       22.01       22.37
          2 |      3,441       34.41       56.78
          3 |      1,897       18.97       75.75
          4 |        747        7.47       83.22
          5 |        384        3.84       87.06
          6 |        247        2.47       89.53
          7 |        180        1.80       91.33
          8 |        126        1.26       92.59
          9 |         86        0.86       93.45
         99 |        655        6.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 21 Jan 2016