Frequencies for first 10,000 rows of mpre6 variable in natl1977 dataset :

      Month |
   Prenatal |
 Care began |
   Recode 6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,445       44.45       44.45
          2 |      2,384       23.84       68.29
          3 |      2,441       24.41       92.70
          4 |        541        5.41       98.11
          5 |        124        1.24       99.35
          6 |         65        0.65      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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