Frequencies for first 10,000 rows of f_mpcb variable in natl2006 dataset :

      Month |
   Prenatal |
 Care Began |
   (precare |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,993       99.93       99.93
          1 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015