Frequencies for first 10,000 rows of mpre6 variable in natl1981 dataset :

      Month |
   Prenatal |
 Care began |
   Recode 6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,787       47.87       47.87
          2 |      2,315       23.15       71.02
          3 |      2,242       22.42       93.44
          4 |        441        4.41       97.85
          5 |        142        1.42       99.27
          6 |         73        0.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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