Frequencies for first 10,000 rows of mpre6 variable in natl1988 dataset :

      Month |
   Prenatal |
 Care began |
   Recode 6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      5,223       52.23       52.23
          2 |      1,904       19.04       71.27
          3 |      2,116       21.16       92.43
          4 |        471        4.71       97.14
          5 |        206        2.06       99.20
          6 |         80        0.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016