Frequencies for first 10,000 rows of mpre10 variable in natl1975 dataset :

      Month |
   Prenatal |
 Care began |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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