Frequencies for first 10,000 rows of mpre6 variable in natl1990 dataset :

      Month |
   Prenatal |
 Care Began |
   Recode 6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      5,226       52.26       52.26
          2 |      2,060       20.60       72.86
          3 |      2,016       20.16       93.02
          4 |        379        3.79       96.81
          5 |        189        1.89       98.70
          6 |        130        1.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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